Re: [Intel-gfx] [igt-dev] [PATCH i-g-t] [RFC] tests/kms_big_fb: Wait for vblank before collecting CRC

[Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>]

On 8.6.2021 10.01, Modem, Bhanuprakash wrote:
>> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Vidya
>> Srinivas
>> Sent: Friday, May 28, 2021 9:57 AM
>> To: intel-gfx@lists.freedesktop.org; igt-dev@lists.freedesktop.org
>> Cc: markyacoub@chromium.org; Lin, Charlton <charlton.lin@intel.com>
>> Subject: [Intel-gfx] [PATCH i-g-t] [RFC] tests/kms_big_fb: Wait for vblank
>> before collecting CRC
>>
>> Without wait for vblank, CRC mismatch is seen
>> between big and small CRC on few Gen11 systems.
>>
>> Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
>> ---
>>   tests/kms_big_fb.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/tests/kms_big_fb.c b/tests/kms_big_fb.c
>> index b35727a09bd0..f90363c3beb2 100644
>> --- a/tests/kms_big_fb.c
>> +++ b/tests/kms_big_fb.c
>> @@ -254,6 +254,7 @@ static void unset_lut(data_t *data)
>>   static bool test_plane(data_t *data)
>>   {
>>   	igt_plane_t *plane = data->plane;
>> +	igt_display_t *display = &data->display;
> 
> For code readability purpose, I think we need to update to use this variable
> wherever we are using "&data->display" in this function.
> s/"&data->display"/"display"/
> 
> With above change, this patch LGTM
> Reviewed-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
> 

I still don't see benefit in this patch. For now all this look like is 
doing is slow down the test and if this actually helps there's a real 
bug somewhere which is not here. My earlier review comments were not 
addressed hence repeat here, see below.


>>   	struct igt_fb *small_fb = &data->small_fb;
>>   	struct igt_fb *big_fb = &data->big_fb;
>>   	int w = data->big_fb_width - small_fb->width;
>> @@ -337,16 +338,17 @@ static bool test_plane(data_t *data)
>>   		igt_display_commit2(&data->display, data->display.is_atomic ?
>>   				    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
>>
>> -
>> +		igt_wait_for_vblank(data->drm_fd, display->pipes[data->pipe].crtc_offset);

Above this line there's flip to different fb. Below this line crc 
calculation is restarted, get one crc and stop crc. There's several 
vblanks already spent here, if now adding one more somehow helps it 
sound like there's problems in crc calculation on some platform or 
kernel is saying too early framebuffer is ready to be shown. Am I 
missing something here?

/Juha-Pekka

>>   		igt_pipe_crc_collect_crc(data->pipe_crc, &small_crc);
>>
>>   		igt_plane_set_fb(plane, big_fb);
>>   		igt_fb_set_position(big_fb, plane, x, y);
>>   		igt_fb_set_size(big_fb, plane, small_fb->width, small_fb->height);
>> +

spurious empty line need to be removed.

>>   		igt_plane_set_size(plane, data->width, data->height);
>>   		igt_display_commit2(&data->display, data->display.is_atomic ?
>>   				    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
>> -
>> +		igt_wait_for_vblank(data->drm_fd, display->pipes[data->pipe].crtc_offset);
>>   		igt_pipe_crc_collect_crc(data->pipe_crc, &big_crc);
>>
>>   		igt_plane_set_fb(plane, NULL);
>> --
>> 2.7.4
>>
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