Re: [i-g-t,v3] tests/kms_bw: Allow custom modes for external panels

[Karthik B S <karthik.b.s@intel.com>]

Hi Kunal,

On 4/21/2026 10:48 AM, Joshi, Kunal1 wrote:
>
> On 20-04-2026 11:42, Karthik B S wrote:
>> Currently, the test is rejecting outputs where the mode does not match.
>> This is leading to excessive skips on configs where the tests
>> were passing previously.
>>
>> Instead of this, use default mode for fixed-mode panels if the required
>> custom mode is not found, and use custom mode for external panels as
>> these are allowed and have also been passing previously.
>>
>> v2: Fixes in output_supported_mode (Kunal)
>>      Add description to call out fixed-mode on internal panels (Kunal)
>>
>> v3: Fix documentation issue on compilation.
>>
>> Cc: Jason-JH Lin <jason-jh.lin@mediatek.com>
>> Cc: Kunal Joshi <kunal1.joshi@intel.com>
>> Signed-off-by: Karthik B S <karthik.b.s@intel.com>
>> Tested-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
>> ---
>>   tests/kms_bw.c | 82 +++++++++++++++++++++++++++++++++++---------------
>>   1 file changed, 58 insertions(+), 24 deletions(-)
>>
>> diff --git a/tests/kms_bw.c b/tests/kms_bw.c
>> index 4df5c2cee..fea7d9d38 100644
>> --- a/tests/kms_bw.c
>> +++ b/tests/kms_bw.c
>> @@ -35,7 +35,7 @@
>>   #include <xf86drmMode.h>
>>     /**
>> - * SUBTEST: linear-tiling-%d-displays-%s
>> + * SUBTEST: linear-tiling-%d-displays-target-%s
>>    * Description: bw test with %arg[2]
>>    *
>>    * arg[1].values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 
>> 15, 16
>> @@ -47,7 +47,7 @@
>>    * @3840x2160p:       3840x2160 resolution
>>    * @2160x1440p:       2160x1440 resolution
>>    *
>> - * SUBTEST: connected-linear-tiling-%d-displays-%s
>> + * SUBTEST: connected-linear-tiling-%d-displays-target-%s
>>    * Description: bw test with %arg[2]
>>    *
>>    * arg[1].values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 
>> 15, 16
>> @@ -186,14 +186,16 @@ static void force_output_mode(data_t *d, 
>> igt_output_t *output,
>>       igt_output_override_mode(output, mode);
>>   }
>>   -static bool output_mode_supported(igt_output_t *output, const 
>> drmModeModeInfo *mode)
>> +/* Check if output has a matching mode and call it out if mode is 
>> being forced */
>> +static void log_output_mode_support(igt_output_t *output, const 
>> drmModeModeInfo *mode)
>>   {
>>       drmModeConnector *connector = output->config.connector;
>> +    drmModeModeInfo *default_mode;
>>       int i;
>>         /* Virtual/forced sinks support all modes */
>>       if (!igt_output_is_connected(output))
>> -        return true;
>> +        return;
>>         for (i = 0; i < connector->count_modes; i++) {
>>           drmModeModeInfo *conn_mode = &connector->modes[i];
>> @@ -204,26 +206,33 @@ static bool output_mode_supported(igt_output_t 
>> *output, const drmModeModeInfo *m
>>               igt_debug("Found matching mode for %dx%d@%dHz on %s\n",
>>                     mode->hdisplay, mode->vdisplay, mode->vrefresh,
>>                     igt_output_name(output));
>> -            return true;
>> +            return;
>>           }
>>       }
>>   -    igt_info("Mode %dx%d@%dHz not supported by %s (has %d modes)\n",
>> -         mode->hdisplay, mode->vdisplay, mode->vrefresh,
>> -         igt_output_name(output), connector->count_modes);
>> -
>> -    return false;
>> +    if (output_is_internal_panel(output)) {
>> +        default_mode = igt_output_get_mode(output);
>> +        igt_info("Mode %dx%d@%dHz not supported by %s (has %d 
>> modes).\n"
>> +             "%s Default mode: %dx%d@%dHz\n",
>> +             mode->hdisplay, mode->vdisplay, mode->vrefresh,
>> +             igt_output_name(output), connector->count_modes, 
>> igt_output_name(output),
>> +             default_mode->hdisplay, default_mode->vdisplay, 
>> default_mode->vrefresh);
>> +    } else {
>> +        igt_info("Mode %dx%d@%dHz not supported by %s (has %d 
>> modes). Forcing mode.\n",
>> +             mode->hdisplay, mode->vdisplay, mode->vrefresh,
>> +             igt_output_name(output), connector->count_modes);
>> +    }
>>   }
>>     static void run_test_linear_tiling(data_t *data, int n_crtcs, 
>> const drmModeModeInfo *mode, bool physical) {
>>       igt_display_t *display = &data->display;
>>       igt_output_t *output;
>> +    drmModeModeInfo fb_mode;
>>       struct igt_fb buffer[IGT_MAX_PIPES];
>>       igt_crc_t zero, captured[IGT_MAX_PIPES];
>>       int i = 0, num_pipes = 0;
>>       igt_crtc_t *crtc;
>>       int ret;
>> -    bool has_supported_mode = false;
>>         /* Cannot use igt_display_n_crtcs() due to fused pipes on 
>> i915 where they do
>>        * not give the numver of valid crtcs and always return 
>> IGT_MAX_PIPES */
>> @@ -242,14 +251,28 @@ static void run_test_linear_tiling(data_t 
>> *data, int n_crtcs, const drmModeModeI
>>           crtc = data->crtc[i];
>>             output = physical ? data->connected_output[i] : 
>> data->output[i];
>> -        if (!output || !output_mode_supported(output, mode)) {
>> +        if (!output)
>>               continue;
>> -        }
>>   -        force_output_mode(data, output, mode);
>> +        log_output_mode_support(output, mode);
>> +
>> +        /*
>> +         * On fixed mode panels trying to force a custom mode can lead
>> +         * to failures or implicit handling where the default mode is
>> +         * used even though custom mode is requested.
>> +         *
>> +         * To avoid this use default mode on fixed mode panels and
>> +         * use custom modes only on external panels.
>> +         */
>> +        if (output_is_internal_panel(output)) {
>> +            fb_mode = *igt_output_get_mode(output);
>> +        } else {
>> +            force_output_mode(data, output, mode);
>> +            fb_mode = *mode;
>> +        }
>>   -        igt_create_color_fb(display->drm_fd, mode->hdisplay,
>> -                    mode->vdisplay, DRM_FORMAT_XRGB8888,
>> +        igt_create_color_fb(display->drm_fd, fb_mode.hdisplay,
>> +                    fb_mode.vdisplay, DRM_FORMAT_XRGB8888,
>>                       DRM_FORMAT_MOD_LINEAR, 1.f, 0.f, 0.f,
>>                       &buffer[i]);
>>   @@ -258,10 +281,8 @@ static void run_test_linear_tiling(data_t 
>> *data, int n_crtcs, const drmModeModeI
>>           igt_plane_set_fb(data->primary[i], &buffer[i]);
>>           igt_info("Assigning pipe %s to output %s with mode %s\n",
>>                igt_crtc_name(crtc), igt_output_name(output),
>> -             mode->name);
>> -        has_supported_mode = true;
>> +             fb_mode.name);
>>       }
>> -    igt_skip_on_f(!has_supported_mode, "Unsupported mode for all 
>> pipes\n");
>>         ret = igt_display_try_commit_atomic(display,
>>                           DRM_MODE_ATOMIC_ALLOW_MODESET |
>> @@ -273,9 +294,8 @@ static void run_test_linear_tiling(data_t *data, 
>> int n_crtcs, const drmModeModeI
>>         for (i = 0; i < n_crtcs; i++) {
>>           output = physical ? data->connected_output[i] : 
>> data->output[i];
>> -        if (!output || !output_mode_supported(output, mode)) {
>> +        if (!output)
>>               continue;
>> -        }
>>             igt_pipe_crc_collect_crc(data->pipe_crc[i], &captured[i]);
>>           igt_assert_f(!igt_check_crc_equal(&zero, &captured[i]),
>> @@ -284,7 +304,7 @@ static void run_test_linear_tiling(data_t *data, 
>> int n_crtcs, const drmModeModeI
>>         for (i = n_crtcs - 1; i >= 0; i--) {
>>           output = physical ? data->connected_output[i] : 
>> data->output[i];
>> -        if (!output || !output_mode_supported(output, mode))
>> +        if (!output)
>>               continue;
>>             igt_remove_fb(display->drm_fd, &buffer[i]);
>> @@ -319,7 +339,14 @@ int igt_main()
>>           n_crtcs = i + 1;
>>             for (j = 0; j < ARRAY_SIZE(test_mode); j++) {
>> -            igt_subtest_f("linear-tiling-%d-displays-%s", n_crtcs, 
>> test_mode[j].name)
>> +            igt_describe("Exercise bandwidth test using linear 
>> tiling across multiple pipes "
>> +                     "on a combination of phical and/or virtual 
>> outputs."
> NIT : Typo : physical
> Can be fixed while merging.
>> +                     "The test targets a bandwidth configuration 
>> corresponding to the "
>> +                     "requested mode, forcing the mode on external 
>> or virtual outputs"
>> +                     "(where supported).On fixed-mode internal 
>> panels, if the native mode "
>> +                     "is used even if it does not match the 
>> requested mode.");
>> + igt_subtest_f("linear-tiling-%d-displays-target-%s",
>> +                      n_crtcs, test_mode[j].name)
>>                   run_test_linear_tiling(&data, n_crtcs, 
>> &test_mode[j], false);
>>           }
>>       }
>> @@ -328,7 +355,14 @@ int igt_main()
>>           n_crtcs = i + 1;
>>                     for (j = 0; j < ARRAY_SIZE(test_mode); j++) {
>> - igt_subtest_f("connected-linear-tiling-%d-displays-%s", n_crtcs, 
>> test_mode[j].name)
>> +            igt_describe("Exercise bandwidth test using linear 
>> tiling across multiple pipes "
>> +                     "on physically connected outputs only."
>> +                     "The test targets a bandwidth configuration 
>> corresponding to the "
>> +                     "requested mode, forcing the mode on external 
>> panels."
>> +                     "On fixed-mode internal panels, if the native 
>> mode "
>> +                     "is used even if it does not match the 
>> requested mode.");
> NIT : Remove if, Can be fixed while merging
> On fixed-mode internal panels, [if] the native mode is used even if it 
> does not match the requested mode.
> On fixed-mode internal panels, the native mode is used even if it does 
> not match the requested mode.
>
> LGTM
> Reviewed-by: Kunal Joshi <kunal1.joshi@intel.com>

Thank you for the RB.

Will make these updates during merge.

Thanks and Regards,
Karthik.B.S
>> + igt_subtest_f("connected-linear-tiling-%d-displays-target-%s",
>> +                      n_crtcs, test_mode[j].name)
>>                   run_test_linear_tiling(&data, n_crtcs, 
>> &test_mode[j], true);
>>                   }
>>           }