Re: [PATCH v17 21/28] drm/tests: bridge: Add KUnit tests for bridge chain format selection

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 09 Jun 2026, Nicolas Frattaroli <nicolas.frattaroli@collabora.com> wrote:
> diff --git a/drivers/gpu/drm/tests/drm_bridge_test.c b/drivers/gpu/drm/tests/drm_bridge_test.c
> index 64b665580a88..92f142ca6695 100644
> --- a/drivers/gpu/drm/tests/drm_bridge_test.c
> +++ b/drivers/gpu/drm/tests/drm_bridge_test.c
> @@ -2,15 +2,23 @@
>  /*
>   * Kunit test for drm_bridge functions
>   */
> +#include <linux/cleanup.h>
> +#include <linux/media-bus-format.h>
> +
>  #include <drm/drm_atomic_state_helper.h>
> +#include <drm/drm_atomic_uapi.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_bridge_connector.h>
>  #include <drm/drm_bridge_helper.h>
> +#include <drm/drm_edid.h>
>  #include <drm/drm_kunit_helpers.h>
> +#include <drm/drm_managed.h>
>  
>  #include <kunit/device.h>
>  #include <kunit/test.h>
>  
> +#include "drm_kunit_edid.h"

So here's the problem with adding *any* arrays into headers: every
compilation unit that includes them duplicates all the arrays. It's only
really okay for single use.

And, in this case, most of the included arrays are unused, leading to
build failures:

  CC [M]  drivers/gpu/drm/tests/drm_bridge_test.o
In file included from ../drivers/gpu/drm/tests/drm_bridge_test.c:21:
../drivers/gpu/drm/tests/drm_kunit_edid.h:958:28: error: ‘test_edid_hdmi_4k_rgb_yuv420_dc_max_340mhz’ defined but not used [-Werror=unused-const-variable=]
  958 | static const unsigned char test_edid_hdmi_4k_rgb_yuv420_dc_max_340mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:726:28: error: ‘test_edid_hdmi_1080p_rgb_yuv_dc_max_340mhz’ defined but not used [-Werror=unused-const-variable=]
  726 | static const unsigned char test_edid_hdmi_1080p_rgb_yuv_dc_max_340mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:612:28: error: ‘test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz’ defined but not used [-Werror=unused-const-variable=]
  612 | static const unsigned char test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:498:28: error: ‘test_edid_hdmi_1080p_rgb_max_340mhz’ defined but not used [-Werror=unused-const-variable=]
  498 | static const unsigned char test_edid_hdmi_1080p_rgb_max_340mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:390:28: error: ‘test_edid_hdmi_1080p_rgb_max_200mhz_hdr’ defined but not used [-Werror=unused-const-variable=]
  390 | static const unsigned char test_edid_hdmi_1080p_rgb_max_200mhz_hdr[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:271:28: error: ‘test_edid_hdmi_1080p_rgb_max_200mhz’ defined but not used [-Werror=unused-const-variable=]
  271 | static const unsigned char test_edid_hdmi_1080p_rgb_max_200mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:163:28: error: ‘test_edid_hdmi_1080p_rgb_max_100mhz’ defined but not used [-Werror=unused-const-variable=]
  163 | static const unsigned char test_edid_hdmi_1080p_rgb_max_100mhz[] = {
      |                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/tests/drm_kunit_edid.h:57:28: error: ‘test_edid_dvi_1080p’ defined but not used [-Werror=unused-const-variable=]
   57 | static const unsigned char test_edid_dvi_1080p[] = {
      |                            ^~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

This breaks the build for me, I don't know how it didn't for any of you.

Reverting these two fixes it:

ce1d0139adac ("drm/tests: bridge: Add test for HDMI output bus formats helper")
082fbc179c01 ("drm/tests: bridge: Add KUnit tests for bridge chain format selection")

I think the proper fix would be to move the arrays into a .c file, and
only have declarations in the headers. But that needs to happen real
soon or the commits need to be reverted.


BR,
Jani.


-- 
Jani Nikula, Intel