Re: [PATCH i-g-t 02/12] tests/amdgpu/amd_multidisplay_modeset: Prepare for returning NULL from igt_crtc_for_pipe()

[Alex Hung <alex.hung@amd.com>]

On 3/18/26 12:03, Kamil Konieczny wrote:
> Hi Jani,
> On 2026-03-16 at 13:19:04 +0200, Jani Nikula wrote:
>> AMD should always have enough CRTCs for the test. Assert this is the
>> case by checking the CRTC is valid.
>>
>> This prepares for returning NULL for invalid pipes from
>> igt_crtc_for_pipe() by ensuring the test logic is sound.
>>
> +cc AMD devs
> Cc: Alex Hung <alex.hung@amd.com>
> Cc: Hersen Wu <hersenxs.wu@amd.com>
> Cc: Vitaly Prosyak <vitaly.prosyak@amd.com>
> 
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>>   tests/amdgpu/amd_multidisplay_modeset.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/tests/amdgpu/amd_multidisplay_modeset.c b/tests/amdgpu/amd_multidisplay_modeset.c
>> index 40d1e5d7f42b..ebcfea8ee35f 100644
>> --- a/tests/amdgpu/amd_multidisplay_modeset.c
>> +++ b/tests/amdgpu/amd_multidisplay_modeset.c
>> @@ -327,6 +327,8 @@ static void multiple_display_test(struct data_t *data, enum sub_test test_mode)
>>   
>>   			crtc = igt_crtc_for_pipe(display, j);
>>   
>> +			igt_assert_f(crtc->valid, "There is no pipe %s\n", kmstest_pipe_name(j));
>> +

As pointed out by Harry in patch 1, igt_crtc_for_pipe can return NULL 
when pipe == PIPE_NONE, and it would be a NULL dereference.

How about just checking crtc?

   "igt_assert_f(crtc, "There is no pipe %s\n", kmstest_pipe_name(j));"

>>   			igt_create_pattern_fb(data->fd, kmode->hdisplay,
>>   					kmode->vdisplay, DRM_FORMAT_XRGB8888,
>>   					0, (buf + j));
>> -- 
>> 2.47.3
>>