[igt-dev] [PATCH i-g-t] tests/kms_plane: survive cdclk caused modeset

[Juha-Pekka Heikkila]

On 7.4.2020 19.08, Ville Syrjälä wrote:
> On Tue, Apr 07, 2020 at 06:54:09PM +0300, Juha-Pekka Heikkila wrote:
>> On 7.4.2020 18.36, Ville Syrjälä wrote:
>>> On Tue, Apr 07, 2020 at 02:09:04PM +0300, Juha-Pekka Heikkila wrote:
>>>> This change will slow this test down a bit. In mid test starting
>>>> to use higher bpp pixel format (say 64bpp) can cause modeset.
>>>> Use blocking commit so there's wait for modeset to happen.
>>>
>>> We already wait for the event the next time around. So this
>>> doesn't make sense to me.
>>
>> There's those logs like this
>> https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_470/fi-icl-guc/igt@kms_plane@pixel-format-pipe-c-planes-source-clamping.html
>>
>> where going to 64bpp pixel format will cause modeset and fail running
>> test.
> 
> Hmm. Seems we don't have drm.debug=0x10 enabled so we don't see the
> actual debug message :( Anyways, the real bug seems to be the lack of
> ALLOW_MODESET.

I'll try that and see how it changes situation. I originally had idea 
modeset will block the flip and making this commit blocking would always 
force things always into correct order as current test didn't fail every 
time for me.

> 
>> I was testing this on ICL and see errors randomly, on ci those
>> seem to be less random. Making this one commit blocking will cause
>> modeset to settle without interrupting test, at least on my ICL.
>>
>> If there's a way to sort those pixel formats according to bpp and start
>> with highest there's no need for this.
>>
>>>
>>>>
>>>> Fixes: https://gitlab.freedesktop.org/drm/intel/issues/1214
>>>> Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
>>>> ---
>>>>    tests/kms_plane.c | 6 ++----
>>>>    1 file changed, 2 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/tests/kms_plane.c b/tests/kms_plane.c
>>>> index 805795cd..2324fb6e 100644
>>>> --- a/tests/kms_plane.c
>>>> +++ b/tests/kms_plane.c
>>>> @@ -569,12 +569,10 @@ static void capture_format_crcs(data_t *data, enum pipe pipe,
>>>>    
>>>>    		if (data->display.is_atomic) {
>>>>    			/*
>>>> -			 * Use non-blocking commits to allow the next fb
>>>> -			 * to be prepared in parallel while the current fb
>>>> -			 * awaits to be latched.
>>>> +			 * Use blocking commit because there maybe
>>>> +			 * modeset when going to higher bpp pixel format.
>>>>    			 */
>>>>    			igt_display_commit_atomic(&data->display,
>>>> -						  DRM_MODE_ATOMIC_NONBLOCK |
>>>>    						  DRM_MODE_PAGE_FLIP_EVENT, NULL);
>>>>    		} else {
>>>>    			/*
>>>> -- 
>>>> 2.17.1
>>>>
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>>>
>