From cc9fde08912150d0cfc9b1b3f7df9b6a9a5665d8 Mon Sep 17 00:00:00 2001
From: Ed <ed@xmos.com>
Date: Fri, 13 Mar 2026 14:31:04 +0000
Subject: [PATCH 1/2] Add CONTROL_INTERFACES_NUM to internals

---
 examples/i2c/device/src/main.xc              |  4 +--
 lib_device_control/adapters/transport_i2c.xc |  6 ++---
 lib_device_control/api/control.h             | 22 ++++++++--------
 lib_device_control/inc/transport_i2c.h       |  3 ++-
 lib_device_control/src/control.xc            | 27 ++++++++++----------
 5 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/examples/i2c/device/src/main.xc b/examples/i2c/device/src/main.xc
index 93b254c0..5ae81643 100644
--- a/examples/i2c/device/src/main.xc
+++ b/examples/i2c/device/src/main.xc
@@ -28,11 +28,9 @@ int main(void)
       control_init();
       control_register_resources(i_control, CONTROL_INTERFACES_NUM);
 
-      /* bug 17317 - [[combine]] */
       par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
+        [[distribute]]
         i2c_control_client(i_i2c, i_control);
-#pragma warning enable
         i2c_slave(i_i2c, p_scl, p_sda, i2c_device_addr);
       }
     }
diff --git a/lib_device_control/adapters/transport_i2c.xc b/lib_device_control/adapters/transport_i2c.xc
index 84b98545..ce4087a4 100644
--- a/lib_device_control/adapters/transport_i2c.xc
+++ b/lib_device_control/adapters/transport_i2c.xc
@@ -14,13 +14,12 @@
 //
 // To include this file in the build, define CONTROL_USE_I2C as 1, in control_conf.h
 
-// [[distributable]]
-void i2c_control_client(server i2c_slave_callback_if i_i2c, client interface control i_control[])
+[[distributable]]
+void i2c_control_client(server i2c_slave_callback_if i_i2c, client interface control i_control[CONTROL_INTERFACES_NUM])
 {
   while (1) {
     select {
       case i_i2c.ack_write_request(void) -> i2c_slave_ack_t resp:
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
         if (control_process_i2c_write_start(i_control) == CONTROL_SUCCESS)
           resp = I2C_SLAVE_ACK;
         else
@@ -47,7 +46,6 @@ void i2c_control_client(server i2c_slave_callback_if i_i2c, client interface con
       case i_i2c.stop_bit(void):
         control_process_i2c_stop(i_control);
         break;
-#pragma warning enable
 
     }
   }
diff --git a/lib_device_control/api/control.h b/lib_device_control/api/control.h
index d1966f68..aae28e28 100644
--- a/lib_device_control/api/control.h
+++ b/lib_device_control/api/control.h
@@ -125,7 +125,7 @@ control_register_resources(CLIENT_INTERFACE_ARRAY(control, i, n), unsigned n);
    *  \returns          Whether the write start was successful or not
    */
 control_ret_t
-control_process_i2c_write_start(CLIENT_INTERFACE(control, i[]));
+control_process_i2c_write_start(CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that an I2C slave read has started. Called from I2C callback API.
    *
@@ -134,7 +134,7 @@ control_process_i2c_write_start(CLIENT_INTERFACE(control, i[]));
    *  \returns          Whether the read start was successful or not
    */
 control_ret_t
-control_process_i2c_read_start(CLIENT_INTERFACE(control, i[]));
+control_process_i2c_read_start(CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that an I2C slave write has occurred. Called from I2C callback API.
    *
@@ -145,7 +145,7 @@ control_process_i2c_read_start(CLIENT_INTERFACE(control, i[]));
    */
 control_ret_t
 control_process_i2c_write_data(const uint8_t data,
-                               CLIENT_INTERFACE(control, i[]));
+                               CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that an I2C slave read has occurred. Called from I2C callback API.
    *
@@ -156,7 +156,7 @@ control_process_i2c_write_data(const uint8_t data,
    */
 control_ret_t
 control_process_i2c_read_data(REFERENCE_PARAM(uint8_t, data),
-                              CLIENT_INTERFACE(control, i[]));
+                              CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that an I2C transaction has stopped. Called from I2C callback API.
    *
@@ -165,7 +165,7 @@ control_process_i2c_read_data(REFERENCE_PARAM(uint8_t, data),
    *  \returns          Whether the stop was successful or not
    */
 control_ret_t
-control_process_i2c_stop(CLIENT_INTERFACE(control, i[]));
+control_process_i2c_stop(CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that a USB set (write) has occurred. Called from USB EP0 handler.
    *
@@ -180,7 +180,7 @@ control_process_i2c_stop(CLIENT_INTERFACE(control, i[]));
 control_ret_t
 control_process_usb_set_request(uint16_t windex, uint16_t wvalue, uint16_t wlength,
                                 const uint8_t request_data[],
-                                CLIENT_INTERFACE(control, i[]));
+                                CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that a USB get (read) has occurred. Called from USB EP0 handler.
    *
@@ -195,7 +195,7 @@ control_process_usb_set_request(uint16_t windex, uint16_t wvalue, uint16_t wleng
 control_ret_t
 control_process_usb_get_request(uint16_t windex, uint16_t wvalue, uint16_t wlength,
                                 uint8_t request_data[],
-                                CLIENT_INTERFACE(control, i[]));
+                                CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that an xscope transfer has occurred. Called from xscope handler.
    *  This function both reads and writes data in a single call.
@@ -213,7 +213,7 @@ control_process_usb_get_request(uint16_t windex, uint16_t wvalue, uint16_t wleng
 control_ret_t
 control_process_xscope_upload(uint8_t buf[], unsigned buf_size,
                               unsigned length_in, REFERENCE_PARAM(unsigned, length_out),
-                              CLIENT_INTERFACE(control, i[]));
+                              CLIENT_INTERFACE(control, i[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that the SPI master has ended the transaction. If the command
    *  was a write, this is the point that a write command is emitted on the i_ctl interface.
@@ -223,7 +223,7 @@ control_process_xscope_upload(uint8_t buf[], unsigned buf_size,
    *  \returns                Whether the transfer was successful or not
    */
 control_ret_t
-control_process_spi_master_ends_transaction(CLIENT_INTERFACE(control, i_ctl[]));
+control_process_spi_master_ends_transaction(CLIENT_INTERFACE(control, i_ctl[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that the SPI master requires data. If the command
    *  was a read, then this is the point that a read command is emitted on the i_ctl interface.
@@ -236,7 +236,7 @@ control_process_spi_master_ends_transaction(CLIENT_INTERFACE(control, i_ctl[]));
    *  \returns                Whether the transfer was successful or not
    */
 control_ret_t
-control_process_spi_master_requires_data(REFERENCE_PARAM(uint32_t, data), CLIENT_INTERFACE(control, i_ctl[]));
+control_process_spi_master_requires_data(REFERENCE_PARAM(uint32_t, data), CLIENT_INTERFACE(control, i_ctl[CONTROL_INTERFACES_NUM]));
 
   /** Inform the control library that the SPI master supplied data.
    *  NOTE: It is assumed that the datum is 8 bits wide, i.e. spi_slave(...) is set up with
@@ -249,6 +249,6 @@ control_process_spi_master_requires_data(REFERENCE_PARAM(uint32_t, data), CLIENT
    *  \returns                Whether the transfer was successful or not
    */
 control_ret_t
-control_process_spi_master_supplied_data(uint32_t datum, uint32_t valid_bits, CLIENT_INTERFACE(control, i_ctl[]));
+control_process_spi_master_supplied_data(uint32_t datum, uint32_t valid_bits, CLIENT_INTERFACE(control, i_ctl[CONTROL_INTERFACES_NUM]));
 
 #endif // CONTROL_H
diff --git a/lib_device_control/inc/transport_i2c.h b/lib_device_control/inc/transport_i2c.h
index 52458a93..ce9b1abb 100644
--- a/lib_device_control/inc/transport_i2c.h
+++ b/lib_device_control/inc/transport_i2c.h
@@ -14,6 +14,7 @@
  * \param i_control Control interface array
  * 
  */
-void i2c_control_client(SERVER_INTERFACE(i2c_slave_callback_if, i_i2c), CLIENT_INTERFACE(control, i_control[]));
+[[distributable]]
+void i2c_control_client(SERVER_INTERFACE(i2c_slave_callback_if, i_i2c), CLIENT_INTERFACE(control, i_control[CONTROL_INTERFACES_NUM]));
 
 #endif // TRANSPORT_I2C_H
diff --git a/lib_device_control/src/control.xc b/lib_device_control/src/control.xc
index 5daeea83..f08221f9 100644
--- a/lib_device_control/src/control.xc
+++ b/lib_device_control/src/control.xc
@@ -42,6 +42,7 @@ control_ret_t control_register_resources(client interface control i[n], unsigned
   ret = CONTROL_SUCCESS;
 
   for (j = 0; j < n; j++) {
+    printf("registering resources for interface %d\n", j);
     i[j].register_resources(r, n0);
     if (resource_table_add(r, n0, j) != 0)
       ret = CONTROL_REGISTRATION_FAILED;
@@ -109,7 +110,7 @@ special_read_command(control_cmd_t cmd, uint8_t payload[], unsigned payload_len)
 }
 
 static control_ret_t
-write_command(client interface control i[],
+write_command(client interface control i[CONTROL_INTERFACES_NUM],
               unsigned char ifnum, control_resid_t resid, control_cmd_t cmd,
               const uint8_t payload[], unsigned payload_len)
 {
@@ -130,7 +131,7 @@ write_command(client interface control i[],
 }
 
 static control_ret_t
-read_command(client interface control i[],
+read_command(client interface control i[CONTROL_INTERFACES_NUM],
              unsigned char ifnum, control_resid_t resid, control_cmd_t cmd,
              uint8_t payload[], unsigned payload_len)
 {
@@ -148,7 +149,7 @@ read_command(client interface control i[],
 }
 
 control_ret_t
-control_process_i2c_write_start(client interface control i[])
+control_process_i2c_write_start(client interface control i[CONTROL_INTERFACES_NUM])
 {
   UNUSED_RES(i);
   // always start a new command
@@ -158,7 +159,7 @@ control_process_i2c_write_start(client interface control i[])
 }
 
 control_ret_t
-control_process_i2c_write_data(const uint8_t data, client interface control i[])
+control_process_i2c_write_data(const uint8_t data, client interface control i[CONTROL_INTERFACES_NUM])
 {
   unsigned char ifnum;
   control_ret_t ret = CONTROL_ERROR;
@@ -250,7 +251,7 @@ control_process_i2c_write_data(const uint8_t data, client interface control i[])
 }
 
 control_ret_t
-control_process_i2c_read_start(client interface control i[])
+control_process_i2c_read_start(client interface control i[CONTROL_INTERFACES_NUM])
 {
   control_ret_t ret;
 
@@ -284,7 +285,7 @@ control_process_i2c_read_start(client interface control i[])
 }
 
 control_ret_t
-control_process_i2c_read_data(uint8_t &data, client interface control i[])
+control_process_i2c_read_data(uint8_t &data, client interface control i[CONTROL_INTERFACES_NUM])
 {
   UNUSED_RES(i);
 
@@ -313,7 +314,7 @@ control_process_i2c_read_data(uint8_t &data, client interface control i[])
 }
 
 control_ret_t
-control_process_i2c_stop(client interface control i[])
+control_process_i2c_stop(client interface control i[CONTROL_INTERFACES_NUM])
 {
   UNUSED_RES(i);
 
@@ -369,7 +370,7 @@ control_process_i2c_stop(client interface control i[])
 control_ret_t
 control_process_usb_set_request(uint16_t windex, uint16_t wvalue, uint16_t wlength,
                                 const uint8_t request_data[],
-                                client interface control i[])
+                                client interface control i[CONTROL_INTERFACES_NUM])
 {
   unsigned payload_len;
   control_resid_t resid;
@@ -400,7 +401,7 @@ control_process_usb_set_request(uint16_t windex, uint16_t wvalue, uint16_t wleng
 control_ret_t
 control_process_usb_get_request(uint16_t windex, uint16_t wvalue, uint16_t wlength,
                                 uint8_t request_data[],
-                                client interface control i[])
+                                client interface control i[CONTROL_INTERFACES_NUM])
 {
   unsigned payload_len;
   control_resid_t resid;
@@ -427,7 +428,7 @@ control_process_usb_get_request(uint16_t windex, uint16_t wvalue, uint16_t wleng
 control_ret_t
 control_process_xscope_upload(uint8_t buf[], unsigned buf_size,
                               unsigned length_in, unsigned &length_out,
-                              client interface control i[])
+                              client interface control i[CONTROL_INTERFACES_NUM])
 {
   (void)buf_size;
   (void)length_in;
@@ -490,7 +491,7 @@ static struct {
 /************/
 
 control_ret_t
-control_process_spi_master_ends_transaction(client interface control i_ctl[])
+control_process_spi_master_ends_transaction(client interface control i_ctl[CONTROL_INTERFACES_NUM])
 {
   /* Debugging */
   // debug_printf("Recieved: ");
@@ -541,7 +542,7 @@ control_process_spi_master_ends_transaction(client interface control i_ctl[])
 }
 
 control_ret_t
-control_process_spi_master_requires_data(uint32_t &data, client interface control i_ctl[])
+control_process_spi_master_requires_data(uint32_t &data, client interface control i_ctl[CONTROL_INTERFACES_NUM])
 {
   control_ret_t ret = CONTROL_SUCCESS;
   data = 0;
@@ -566,7 +567,7 @@ control_process_spi_master_requires_data(uint32_t &data, client interface contro
 }
 
 control_ret_t
-control_process_spi_master_supplied_data(uint32_t datum, uint32_t valid_bits, client interface control i_ctl[])
+control_process_spi_master_supplied_data(uint32_t datum, uint32_t valid_bits, client interface control i_ctl[CONTROL_INTERFACES_NUM])
 {
   /* Debugging */
   // buffer[buffer_length] = (unsigned char) datum;

From 3bd9650b695e19ceef38c5a17e19cd8d033156f7 Mon Sep 17 00:00:00 2001
From: Ed <ed@xmos.com>
Date: Mon, 16 Mar 2026 15:41:49 +0000
Subject: [PATCH 2/2] Update all arrays with CONTROL_INTERFACES_NUM

---
 examples/spi/device/src/main.xc                |  8 +++-----
 examples/usb/device/src/endpoint0.xc           |  4 ----
 examples/usb/device/src/main.xc                |  2 +-
 examples/xscope/device/src/main.xc             |  4 +---
 lib_device_control/adapters/transport_spi.xc   |  4 +---
 lib_device_control/adapters/transport_usb.xc   |  4 ++--
 .../adapters/transport_xscope.xc               |  6 ++----
 lib_device_control/inc/control_default_conf.h  |  3 +++
 lib_device_control/inc/transport_spi.h         |  2 +-
 lib_device_control/inc/transport_usb.h         |  4 ++--
 lib_device_control/inc/transport_xscope.h      |  2 +-
 lib_device_control/src/control.xc              |  2 --
 tests/i2c_device/src/control_conf.h            |  9 +++++++++
 tests/i2c_device/src/test.xc                   | 18 ++++++++----------
 tests/i2c_end_to_end_sim/src/app_device.xc     |  2 --
 tests/spi_device/src/control_conf.h            |  9 +++++++++
 tests/spi_device/src/test.xc                   | 18 ++++++++----------
 tests/usb_device/src/control_conf.h            |  9 +++++++++
 tests/usb_device/src/test.xc                   | 18 ++++++++----------
 tests/usb_end_to_end_hardware/src/main.xc      |  4 ----
 tests/version/src/test.xc                      |  8 --------
 tests/xscope_device/src/control_conf.h         |  9 +++++++++
 tests/xscope_device/src/test.xc                | 18 ++++++++----------
 23 files changed, 85 insertions(+), 82 deletions(-)
 create mode 100644 tests/i2c_device/src/control_conf.h
 create mode 100644 tests/spi_device/src/control_conf.h
 create mode 100644 tests/usb_device/src/control_conf.h
 create mode 100644 tests/xscope_device/src/control_conf.h

diff --git a/examples/spi/device/src/main.xc b/examples/spi/device/src/main.xc
index 8fb4421f..ea5d126f 100644
--- a/examples/spi/device/src/main.xc
+++ b/examples/spi/device/src/main.xc
@@ -17,15 +17,13 @@ on tile[PORT_SPI_SLAVE_CS_TILE_NUM]: in port                p_ss   = PORT_SPI_SL
 on tile[PORT_SPI_SLAVE_MISO_TILE_NUM]: out buffered port:32 p_miso = PORT_SPI_SLAVE_MISO;
 on tile[PORT_SPI_SLAVE_MOSI_TILE_NUM]: in buffered port:32  p_mosi = PORT_SPI_SLAVE_MOSI;
 
-void spi_ctrl(client interface control i_control[1])
+void spi_ctrl(client interface control i_control[CONTROL_INTERFACES_NUM])
 {
   interface spi_slave_callback_if i_spi;
   control_init();
-  control_register_resources(i_control, 1);
+  control_register_resources(i_control, CONTROL_INTERFACES_NUM);
   par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
     spi_control_client(i_spi, i_control);
-#pragma warning enable
     spi_slave(i_spi, p_sclk, p_mosi, p_miso, p_ss, cb,
               SPI_MODE_3, SPI_TRANSFER_SIZE_8);
   }
@@ -34,7 +32,7 @@ void spi_ctrl(client interface control i_control[1])
 
 int main(void)
 {
-  interface control i_control[1];
+  interface control i_control[CONTROL_INTERFACES_NUM];
   par {
     on tile[PORT_SPI_SLAVE_SCLK_TILE_NUM]: par {
       spi_ctrl(i_control);
diff --git a/examples/usb/device/src/endpoint0.xc b/examples/usb/device/src/endpoint0.xc
index 74b3008a..1e14043b 100644
--- a/examples/usb/device/src/endpoint0.xc
+++ b/examples/usb/device/src/endpoint0.xc
@@ -106,9 +106,7 @@ void Endpoint0(chanend chan_ep0_out, chanend chan_ep0_in, client interface contr
                     break;
 
                 case USB_BMREQ_H2D_VENDOR_DEV:
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                     result = USB_H2D_VendorRequest(ep0_out, ep0_in, &sp, i_control);
-#pragma warning enable
                     break;
 
                 case USB_BMREQ_D2H_VENDOR_DEV:
@@ -116,9 +114,7 @@ void Endpoint0(chanend chan_ep0_out, chanend chan_ep0_in, client interface contr
                         result = XUD_GetMsosDescriptor(ep0_out, ep0_in, &sp);
 
                     } else {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                         result = USB_D2H_VendorRequest(ep0_out, ep0_in, &sp, i_control);
-#pragma warning enable
                     }
                     break;
             }
diff --git a/examples/usb/device/src/main.xc b/examples/usb/device/src/main.xc
index 3512be6a..aade4ad5 100644
--- a/examples/usb/device/src/main.xc
+++ b/examples/usb/device/src/main.xc
@@ -26,7 +26,7 @@ XUD_EpType epTypeTableIn[XUD_EP_COUNT_IN] =   {XUD_EPTYPE_CTL | XUD_STATUS_ENABL
 int main(void)
 {
   chan c_ep_out[XUD_EP_COUNT_OUT], c_ep_in[XUD_EP_COUNT_IN];
-  interface control i_control[1];
+  interface control i_control[CONTROL_INTERFACES_NUM];
   par {
     on USB_TILE: par {
       Endpoint0(c_ep_out[0], c_ep_in[0], i_control);
diff --git a/examples/xscope/device/src/main.xc b/examples/xscope/device/src/main.xc
index 1c6a82d6..5c93e5dd 100644
--- a/examples/xscope/device/src/main.xc
+++ b/examples/xscope/device/src/main.xc
@@ -14,13 +14,11 @@
 int main(void)
 {
   chan c_xscope;
-  interface control i_control[1];
+  interface control i_control[CONTROL_INTERFACES_NUM];
 
   par {
     xscope_host_data(c_xscope);
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
     on tile[0]: xscope_control_client(c_xscope, i_control);
-#pragma warning enable
     on tile[0]: app(i_control[0]);
   }
   return 0;
diff --git a/lib_device_control/adapters/transport_spi.xc b/lib_device_control/adapters/transport_spi.xc
index b4d7db49..9baa4df8 100644
--- a/lib_device_control/adapters/transport_spi.xc
+++ b/lib_device_control/adapters/transport_spi.xc
@@ -14,10 +14,9 @@
 //
 // To include this file in the build, define CONTROL_USE_SPI as 1, in control_conf.h
 
-void spi_control_client(server spi_slave_callback_if i_spi, client interface control i_control[])
+void spi_control_client(server spi_slave_callback_if i_spi, client interface control i_control[CONTROL_INTERFACES_NUM])
 {
   while (1) {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
     select {
       case i_spi.master_ends_transaction():
         control_process_spi_master_ends_transaction(i_control);
@@ -29,7 +28,6 @@ void spi_control_client(server spi_slave_callback_if i_spi, client interface con
         control_process_spi_master_supplied_data(datum, valid_bits, i_control);
         break;
     }
-#pragma warning enable
   }
 }
 
diff --git a/lib_device_control/adapters/transport_usb.xc b/lib_device_control/adapters/transport_usb.xc
index e945b8d1..12fd60e2 100644
--- a/lib_device_control/adapters/transport_usb.xc
+++ b/lib_device_control/adapters/transport_usb.xc
@@ -34,7 +34,7 @@ static XUD_Result_t USB_EP0_Receive(XUD_ep ep0_out, USB_SetupPacket_t *sp, uint8
 }
 
 // case USB_BMREQ_H2D_VENDOR_DEV:
-XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, client interface control i_control[]) {
+XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, client interface control i_control[CONTROL_INTERFACES_NUM]) {
     XUD_Result_t result = XUD_RES_ERR;
     if ((sp->bRequest == CONTROL_VENDOR_REQUEST) && (sp->wLength <= EP0_MAX_REQUEST_SIZE)) {
         result = USB_EP0_Receive(ep0_out, sp, request_data);
@@ -53,7 +53,7 @@ XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacke
 }
 
 // case USB_BMREQ_D2H_VENDOR_DEV:
-XUD_Result_t USB_D2H_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, client interface control i_control[]) {
+XUD_Result_t USB_D2H_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, client interface control i_control[CONTROL_INTERFACES_NUM]) {
     XUD_Result_t result = XUD_RES_ERR;
     if ((sp->bRequest == CONTROL_VENDOR_REQUEST) && (sp->wLength <= EP0_MAX_REQUEST_SIZE)) {
         control_ret_t ctrl = control_process_usb_get_request(sp->wIndex, sp->wValue, sp->wLength, request_data, i_control);
diff --git a/lib_device_control/adapters/transport_xscope.xc b/lib_device_control/adapters/transport_xscope.xc
index 459bcaea..3a1ffdbc 100644
--- a/lib_device_control/adapters/transport_xscope.xc
+++ b/lib_device_control/adapters/transport_xscope.xc
@@ -16,13 +16,13 @@
 #define DEBUG_UNIT TRANSPORT
 #include "debug_print.h"
 
-void xscope_control_client(chanend c_xscope, client interface control i_control[])
+void xscope_control_client(chanend c_xscope, client interface control i_control[CONTROL_INTERFACES_NUM])
 {
   uint8_t buffer[256]; /* 256 bytes from xscope.h */
   int num_bytes_read;
 
   control_init();
-  control_register_resources(i_control, 1);
+  control_register_resources(i_control, CONTROL_INTERFACES_NUM);
 
   xscope_connect_data_from_host(c_xscope);
 
@@ -32,9 +32,7 @@ void xscope_control_client(chanend c_xscope, client interface control i_control[
     select {
       case xscope_data_from_host(c_xscope, buffer, num_bytes_read):
         unsigned return_size;
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
         control_process_xscope_upload(buffer, sizeof(buffer), num_bytes_read, return_size, i_control);
-#pragma warning enable
         if (return_size > 0) {
           xscope_core_bytes(0, return_size, buffer);
         }
diff --git a/lib_device_control/inc/control_default_conf.h b/lib_device_control/inc/control_default_conf.h
index a4348cd1..eabce096 100644
--- a/lib_device_control/inc/control_default_conf.h
+++ b/lib_device_control/inc/control_default_conf.h
@@ -10,6 +10,9 @@
 
 #ifndef CONTROL_INTERFACES_NUM
 #define CONTROL_INTERFACES_NUM 1
+// TODO host apps fail with this warning
+// #warning "CONTROL_INTERFACES_NUM not defined in control_conf.h, defaulting to 1."
+// #warning "Please define CONTROL_INTERFACES_NUM in control_conf.h to silence this warning."
 #endif
 
 #if CONTROL_INTERFACES_NUM <= 0
diff --git a/lib_device_control/inc/transport_spi.h b/lib_device_control/inc/transport_spi.h
index 723bb55a..463f0806 100644
--- a/lib_device_control/inc/transport_spi.h
+++ b/lib_device_control/inc/transport_spi.h
@@ -14,6 +14,6 @@
  * \param i_control Control interface array
  * 
  */
-void spi_control_client(SERVER_INTERFACE(spi_slave_callback_if, i_spi), CLIENT_INTERFACE(control, i_control[]));
+void spi_control_client(SERVER_INTERFACE(spi_slave_callback_if, i_spi), CLIENT_INTERFACE(control, i_control[CONTROL_INTERFACES_NUM]));
 
 #endif // TRANSPORT_SPI_H
diff --git a/lib_device_control/inc/transport_usb.h b/lib_device_control/inc/transport_usb.h
index d8d2d7fa..5403e945 100644
--- a/lib_device_control/inc/transport_usb.h
+++ b/lib_device_control/inc/transport_usb.h
@@ -17,7 +17,7 @@
  * 
  * \return XUD_Result_t Result of the operation
  */
-XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, CLIENT_INTERFACE(control, i_control[]));
+XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, CLIENT_INTERFACE(control, i_control[CONTROL_INTERFACES_NUM]));
 
 /** USB transport host read (Get) processing function
  * \param ep0_out  Endpoint 0 OUT endpoint
@@ -27,6 +27,6 @@ XUD_Result_t USB_H2D_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacke
  * 
  * \return XUD_Result_t Result of the operation
  */
-XUD_Result_t USB_D2H_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, CLIENT_INTERFACE(control, i_control[]));
+XUD_Result_t USB_D2H_VendorRequest(XUD_ep ep0_out, XUD_ep ep0_in, USB_SetupPacket_t *sp, CLIENT_INTERFACE(control, i_control[CONTROL_INTERFACES_NUM]));
 
 #endif // TRANSPORT_USB_H
diff --git a/lib_device_control/inc/transport_xscope.h b/lib_device_control/inc/transport_xscope.h
index 4424e7e7..fbdeac20 100644
--- a/lib_device_control/inc/transport_xscope.h
+++ b/lib_device_control/inc/transport_xscope.h
@@ -14,6 +14,6 @@
  * \param i_control Control interface array
  * 
  */
-void xscope_control_client(chanend c_xscope, CLIENT_INTERFACE(control, i_control[]));
+void xscope_control_client(chanend c_xscope, CLIENT_INTERFACE(control, i_control[CONTROL_INTERFACES_NUM]));
 
 #endif // TRANSPORT_XSCOPE_H
diff --git a/lib_device_control/src/control.xc b/lib_device_control/src/control.xc
index f08221f9..2ae21db3 100644
--- a/lib_device_control/src/control.xc
+++ b/lib_device_control/src/control.xc
@@ -2,7 +2,6 @@
 // This Software is subject to the terms of the XMOS Public Licence: Version 1.
 #include <stdint.h>
 #include <stddef.h>
-#include <stdio.h>
 #include <xscope.h>
 #include "control.h"
 #include "control_transport_shared.h"
@@ -42,7 +41,6 @@ control_ret_t control_register_resources(client interface control i[n], unsigned
   ret = CONTROL_SUCCESS;
 
   for (j = 0; j < n; j++) {
-    printf("registering resources for interface %d\n", j);
     i[j].register_resources(r, n0);
     if (resource_table_add(r, n0, j) != 0)
       ret = CONTROL_REGISTRATION_FAILED;
diff --git a/tests/i2c_device/src/control_conf.h b/tests/i2c_device/src/control_conf.h
new file mode 100644
index 00000000..d7dca21f
--- /dev/null
+++ b/tests/i2c_device/src/control_conf.h
@@ -0,0 +1,9 @@
+// Copyright 2026 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+#ifndef CONTROL_CONF_H
+#define CONTROL_CONF_H
+
+#define CONTROL_INTERFACES_NUM 3
+
+#endif // CONTROL_CONF_H
diff --git a/tests/i2c_device/src/test.xc b/tests/i2c_device/src/test.xc
index feff4958..50f2e1a8 100644
--- a/tests/i2c_device/src/test.xc
+++ b/tests/i2c_device/src/test.xc
@@ -10,7 +10,7 @@
 #include "support_inline.h"
 #include "user_task.h"
 
-void test_client(client interface control i[3], chanend c_user_task[3])
+void test_client(client interface control i[CONTROL_INTERFACES_NUM], chanend c_user_task[CONTROL_INTERFACES_NUM])
 {
   uint8_t buf[I2C_TRANSACTION_MAX_BYTES];
   size_t buf_len;
@@ -32,8 +32,8 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
   /* trigger a registration call, catch it and supply resource IDs to register */
   par {
-    control_register_resources(i, 3);
-    drive_user_task_registration(c_user_task, 3);
+    control_register_resources(i, CONTROL_INTERFACES_NUM);
+    drive_user_task_registration(c_user_task, CONTROL_INTERFACES_NUM);
   }
 
   fails = 0;
@@ -56,7 +56,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
               tmr :> t;
               timeout = 0;
               par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                 { control_ret_t ret;
                   ret = CONTROL_SUCCESS;
                   ret |= control_process_i2c_write_start(i);
@@ -94,7 +93,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
                   d :> ret;
                   fails += check(o, c1, c2, timeout, ret, 3);
                 }
-#pragma warning enable
               }
             }
           }
@@ -115,13 +113,13 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
 int main(void)
 {
-  interface control i[3];
-  chan c_user_task[3];
+  interface control i[CONTROL_INTERFACES_NUM];
+  chan c_user_task[CONTROL_INTERFACES_NUM];
   par {
     test_client(i, c_user_task);
-    user_task(i[0], c_user_task[0]);
-    user_task(i[1], c_user_task[1]);
-    user_task(i[2], c_user_task[2]);
+    par(int t=0; t < CONTROL_INTERFACES_NUM; t++) {
+      user_task(i[t], c_user_task[t]);
+    }
     { delay_microseconds(10000);
       printf("ERROR - test timeout\n");
       exit(1);
diff --git a/tests/i2c_end_to_end_sim/src/app_device.xc b/tests/i2c_end_to_end_sim/src/app_device.xc
index ff98cb35..c12d3864 100644
--- a/tests/i2c_end_to_end_sim/src/app_device.xc
+++ b/tests/i2c_end_to_end_sim/src/app_device.xc
@@ -14,7 +14,6 @@ void i2c_client(server i2c_slave_callback_if i_i2c, client interface control i_c
 
   while (1) {
     select {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
       case i_i2c.ack_write_request(void) -> i2c_slave_ack_t resp:
         if (control_process_i2c_write_start(i_control) == CONTROL_SUCCESS)
           resp = I2C_SLAVE_ACK;
@@ -45,7 +44,6 @@ void i2c_client(server i2c_slave_callback_if i_i2c, client interface control i_c
         control_process_i2c_stop(i_control);
         break;
     }
-#pragma warning enable
   }
 }
 
diff --git a/tests/spi_device/src/control_conf.h b/tests/spi_device/src/control_conf.h
new file mode 100644
index 00000000..d7dca21f
--- /dev/null
+++ b/tests/spi_device/src/control_conf.h
@@ -0,0 +1,9 @@
+// Copyright 2026 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+#ifndef CONTROL_CONF_H
+#define CONTROL_CONF_H
+
+#define CONTROL_INTERFACES_NUM 3
+
+#endif // CONTROL_CONF_H
diff --git a/tests/spi_device/src/test.xc b/tests/spi_device/src/test.xc
index 5b3c5195..a5ac09dd 100644
--- a/tests/spi_device/src/test.xc
+++ b/tests/spi_device/src/test.xc
@@ -10,7 +10,7 @@
 #include "support_inline.h"
 #include "user_task.h"
 
-void test_client(client interface control i[3], chanend c_user_task[3])
+void test_client(client interface control i[CONTROL_INTERFACES_NUM], chanend c_user_task[CONTROL_INTERFACES_NUM])
 {
   uint8_t buf[SPI_TRANSACTION_MAX_BYTES];
   size_t buf_len;
@@ -33,8 +33,8 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
   /* trigger a registration call, catch it and supply resource IDs to register */
   par {
-    control_register_resources(i, 3);
-    drive_user_task_registration(c_user_task, 3);
+    control_register_resources(i, CONTROL_INTERFACES_NUM);
+    drive_user_task_registration(c_user_task, CONTROL_INTERFACES_NUM);
   }
 
   fails = 0;
@@ -58,7 +58,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
               tmr :> t;
               timeout = 0;
               par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                 { control_ret_t ret;
                   ret = CONTROL_SUCCESS;
 
@@ -103,7 +102,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
                   }
                   d <: ret;
                 }
-#pragma warning disable
                 { control_ret_t ret;
                   select {
                     case drive_user_task_commands(c2, c1, c_user_task, o.read_cmd);
@@ -134,13 +132,13 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
 int main(void)
 {
-  interface control i[3];
-  chan c_user_task[3];
+  interface control i[CONTROL_INTERFACES_NUM];
+  chan c_user_task[CONTROL_INTERFACES_NUM];
   par {
     test_client(i, c_user_task);
-    user_task(i[0], c_user_task[0]);
-    user_task(i[1], c_user_task[1]);
-    user_task(i[2], c_user_task[2]);
+    par(int t=0; t < CONTROL_INTERFACES_NUM; t++) {
+      user_task(i[t], c_user_task[t]);
+    }
     { delay_microseconds(10000);
       printf("ERROR - test timeout\n");
       exit(1);
diff --git a/tests/usb_device/src/control_conf.h b/tests/usb_device/src/control_conf.h
new file mode 100644
index 00000000..d7dca21f
--- /dev/null
+++ b/tests/usb_device/src/control_conf.h
@@ -0,0 +1,9 @@
+// Copyright 2026 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+#ifndef CONTROL_CONF_H
+#define CONTROL_CONF_H
+
+#define CONTROL_INTERFACES_NUM 3
+
+#endif // CONTROL_CONF_H
diff --git a/tests/usb_device/src/test.xc b/tests/usb_device/src/test.xc
index 72dad4f1..24f79c39 100644
--- a/tests/usb_device/src/test.xc
+++ b/tests/usb_device/src/test.xc
@@ -10,7 +10,7 @@
 #include "support_inline.h"
 #include "user_task.h"
 
-void test_client(client interface control i[3], chanend c_user_task[3])
+void test_client(client interface control i[CONTROL_INTERFACES_NUM], chanend c_user_task[CONTROL_INTERFACES_NUM])
 {
   uint16_t windex, wvalue, wlength;
   struct command c1, c2;
@@ -31,8 +31,8 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
   /* trigger a registration call, catch it and supply resource IDs to register */
   par {
-    control_register_resources(i, 3);
-    drive_user_task_registration(c_user_task, 3);
+    control_register_resources(i, CONTROL_INTERFACES_NUM);
+    drive_user_task_registration(c_user_task, CONTROL_INTERFACES_NUM);
   }
 
   fails = 0;
@@ -59,7 +59,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
               tmr :> t;
               timeout = 0;
               par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                 { if (o.read_cmd) {
                     d <: control_process_usb_get_request(windex, wvalue, wlength,
                       (uint8_t*)payload_ptr, i);
@@ -74,7 +73,6 @@ void test_client(client interface control i[3], chanend c_user_task[3])
                     d <: payload_ptr[0];
                   }
                 }
-#pragma warning enable
                 { select {
                     case drive_user_task_commands(c2, c1, c_user_task, o.read_cmd);
                     case tmr when timerafter(t + 500) :> void:
@@ -104,13 +102,13 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
 int main(void)
 {
-  interface control i[3];
-  chan c_user_task[3];
+  interface control i[CONTROL_INTERFACES_NUM];
+  chan c_user_task[CONTROL_INTERFACES_NUM];
   par {
     test_client(i, c_user_task);
-    user_task(i[0], c_user_task[0]);
-    user_task(i[1], c_user_task[1]);
-    user_task(i[2], c_user_task[2]);
+    par(int t=0; t < CONTROL_INTERFACES_NUM; t++) {
+      user_task(i[t], c_user_task[t]);
+    }
     { delay_microseconds(5000);
       printf("ERROR - test timeout\n");
       exit(1);
diff --git a/tests/usb_end_to_end_hardware/src/main.xc b/tests/usb_end_to_end_hardware/src/main.xc
index 29fc0e70..704fefaa 100644
--- a/tests/usb_end_to_end_hardware/src/main.xc
+++ b/tests/usb_end_to_end_hardware/src/main.xc
@@ -44,10 +44,8 @@ void endpoint0(chanend c_ep0_out, chanend c_ep0_in, client interface control i_c
         case USB_BMREQ_H2D_VENDOR_DEV:
           res = XUD_GetBuffer(ep0_out, request_data, len);
           if (res == XUD_RES_OKAY) {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
             if (control_process_usb_set_request(sp.wIndex, sp.wValue, sp.wLength,
                                                 request_data, i_control) == CONTROL_SUCCESS) {
-#pragma warning enable
               /* zero length data to indicate success
                * on control error, go to standard requests, which will issue STALL
                */
@@ -60,10 +58,8 @@ void endpoint0(chanend c_ep0_out, chanend c_ep0_in, client interface control i_c
           /* application retrieval latency inside the control library call
            * XUD task defers further calls by NAKing USB transactions
            */
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
           if (control_process_usb_get_request(sp.wIndex, sp.wValue, sp.wLength,
                                               request_data, i_control) == CONTROL_SUCCESS) {
-#pragma warning enable
             len = sp.wLength;
             res = XUD_DoGetRequest(ep0_out, ep0_in, request_data, len, len);
             handled = 1;
diff --git a/tests/version/src/test.xc b/tests/version/src/test.xc
index 55608368..995523a6 100644
--- a/tests/version/src/test.xc
+++ b/tests/version/src/test.xc
@@ -18,9 +18,7 @@ void test_usb(client interface control i[1])
   control_usb_fill_header(&windex, &wvalue, &wlength,
     CONTROL_SPECIAL_RESID, CONTROL_GET_VERSION, sizeof(control_version_t));
 
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
   ret = control_process_usb_get_request(windex, wvalue, wlength, request_data, i);
-#pragma warning disable
   memcpy(&version, request_data, sizeof(control_version_t));
 
   if (ret != CONTROL_SUCCESS) {
@@ -46,7 +44,6 @@ void test_i2c(client interface control i[1])
     CONTROL_GET_VERSION, data, sizeof(control_version_t));
   ret = CONTROL_SUCCESS;
 
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
   ret |= control_process_i2c_write_start(i);
   for (j = 0; j < len; j++) {
     ret |= control_process_i2c_write_data(buf[j], i);
@@ -58,7 +55,6 @@ void test_i2c(client interface control i[1])
 
   memcpy(&version, data, sizeof(control_version_t));
   ret |= control_process_i2c_stop(i);
-#pragma warning enable
 
   if (ret != CONTROL_SUCCESS) {
     printf("ERROR - I2C processing functions returned %d\n", ret);
@@ -85,7 +81,6 @@ void test_spi(client interface control i[1])
   len = control_build_spi_data(buf, CONTROL_SPECIAL_RESID,
     CONTROL_GET_VERSION, (uint8_t*) data, sizeof(control_version_t));
 
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
   // Send message information in a write transaction
   for (j = 0; j < len; j++) {
     ret |= control_process_spi_master_supplied_data(buf[j], SPI_TRANSFER_SIZE_BITS, i);
@@ -102,7 +97,6 @@ void test_spi(client interface control i[1])
   memcpy(&version, data, sizeof(control_version_t));
 
   ret |= control_process_spi_master_ends_transaction(i);
-#pragma warning disable
 
   if (ret != CONTROL_SUCCESS) {
     printf("ERROR - SPI processing functions returned %d\n", ret);
@@ -125,9 +119,7 @@ void test_xscope(client interface control i[1])
   len = control_xscope_create_upload_buffer(buf,
     CONTROL_GET_VERSION, CONTROL_SPECIAL_RESID,
     NULL, sizeof(control_version_t));
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
   ret = control_process_xscope_upload((uint8_t*)buf, sizeof(buf), len, len2, i);
-#pragma warning enable
   resp = (struct control_xscope_response*)buf;
   version = *(control_version_t*)(resp + 1);
 
diff --git a/tests/xscope_device/src/control_conf.h b/tests/xscope_device/src/control_conf.h
new file mode 100644
index 00000000..d7dca21f
--- /dev/null
+++ b/tests/xscope_device/src/control_conf.h
@@ -0,0 +1,9 @@
+// Copyright 2026 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+#ifndef CONTROL_CONF_H
+#define CONTROL_CONF_H
+
+#define CONTROL_INTERFACES_NUM 3
+
+#endif // CONTROL_CONF_H
diff --git a/tests/xscope_device/src/test.xc b/tests/xscope_device/src/test.xc
index 825cf1b5..a8925ef2 100644
--- a/tests/xscope_device/src/test.xc
+++ b/tests/xscope_device/src/test.xc
@@ -13,7 +13,7 @@
 
 #define PRINT_ALL 0
 
-void test_client(client interface control i[3], chanend c_user_task[3])
+void test_client(client interface control i[CONTROL_INTERFACES_NUM], chanend c_user_task[CONTROL_INTERFACES_NUM])
 {
   uint32_t buf[64];
   struct command c1, c2;
@@ -39,8 +39,8 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
   /* trigger a registration call, catch it and supply resource IDs to register */
   par {
-    control_register_resources(i, 3);
-    drive_user_task_registration(c_user_task, 3);
+    control_register_resources(i, CONTROL_INTERFACES_NUM);
+    drive_user_task_registration(c_user_task, CONTROL_INTERFACES_NUM);
   }
 
   fails = 0;
@@ -68,9 +68,7 @@ void test_client(client interface control i[3], chanend c_user_task[3])
               tmr :> t;
               timeout = 0;
               par {
-#pragma warning disable unusual-code // Suppress slice interface warning (no array size passed)
                 d <: control_process_xscope_upload((uint8_t*)buf_ptr, sizeof(buf), lenin, lenout, i);
-#pragma warning enable
                 { const size_t header_len = sizeof(struct control_xscope_response);
                   struct control_xscope_response *resp = (struct control_xscope_response*)buf;
                   uint8_t *payload = (uint8_t*)(resp + 1);
@@ -151,13 +149,13 @@ void test_client(client interface control i[3], chanend c_user_task[3])
 
 int main(void)
 {
-  interface control i[3];
-  chan c_user_task[3];
+  interface control i[CONTROL_INTERFACES_NUM];
+  chan c_user_task[CONTROL_INTERFACES_NUM];
   par {
     test_client(i, c_user_task);
-    user_task(i[0], c_user_task[0]);
-    user_task(i[1], c_user_task[1]);
-    user_task(i[2], c_user_task[2]);
+    par(int t=0; t < CONTROL_INTERFACES_NUM; t++) {
+      user_task(i[t], c_user_task[t]);
+    }
     { delay_microseconds(5000);
       printf("ERROR - test timeout\n");
       exit(1);