[igt-dev] [v3] tests/kms_color: Fix CRC mismatch issues with ctm test

[Shankar, Uma]

>>>
>>> >-----Original Message-----
>>> >From: Ville Syrjälä [mailto:ville.syrjala at linux.intel.com]
>>> >Sent: Wednesday, March 27, 2019 5:05 PM
>>> >To: Shankar, Uma <uma.shankar at intel.com>
>>> >Cc: igt-dev at lists.freedesktop.org; Syrjala, Ville
>>> ><ville.syrjala at intel.com>; Lankhorst, Maarten
>>> ><maarten.lankhorst at intel.com>
>>> >Subject: Re: [igt-dev] [v3] tests/kms_color: Fix CRC mismatch issues
>>> >with ctm test
>>> >
>>> >On Wed, Mar 27, 2019 at 10:52:48AM +0000, Shankar, Uma wrote:
>>> >>
>>> >>
>>> >> >On Wed, Mar 27, 2019 at 06:20:10AM +0000, Shankar, Uma wrote:
>>> >> >>
>>> >> >>
>>> >> >> >-----Original Message-----
>>> >> >> >From: Ville Syrjälä [mailto:ville.syrjala at linux.intel.com]
>>> >> >> >Sent: Tuesday, March 26, 2019 10:16 PM
>>> >> >> >To: Shankar, Uma <uma.shankar at intel.com>
>>> >> >> >Cc: igt-dev at lists.freedesktop.org; Syrjala, Ville
>>> >> >> ><ville.syrjala at intel.com>; Lankhorst, Maarten
>>> >> >> ><maarten.lankhorst at intel.com>
>>> >> >> >Subject: Re: [igt-dev] [v3] tests/kms_color: Fix CRC mismatch
>>> >> >> >issues with ctm test
>>> >> >> >
>>> >> >> >On Tue, Mar 26, 2019 at 10:31:01AM +0000, Shankar, Uma wrote:
>>> >> >> >>
>>> >> >> >>
>>> >> >> >> >-----Original Message-----
>>> >> >> >> >From: Shankar, Uma
>>> >> >> >> >Sent: Monday, March 25, 2019 2:11 PM
>>> >> >> >> >To: igt-dev at lists.freedesktop.org
>>> >> >> >> >Cc: Shankar, Uma <uma.shankar at intel.com>
>>> >> >> >> >Subject: [v3] tests/kms_color: Fix CRC mismatch issues with
>>> >> >> >> >ctm test
>>> >> >> >> >
>>> >> >> >> >Due to Gamma/Degamma limitation with precision (lack of
>>> >> >> >> >exact
>>> >> >> >> >1.0
>>> >> >> >> >representation) due to ABI restriction, applying linear
>>> >> >> >> >gamma affects crc. This patch fixes the same by making ctm
>>> >> >> >> >tests independant of
>>> >> >> >gamma/degamma.
>>> >> >> >> >
>>> >> >> >> >v2: Disable degamma/gamma programming for ctm max test as
>>> >> >> >> >it leads to crc mimsmatch. Limiting it to this test case
>>> >> >> >> >alone as other tests need it to be enabled, hence not touching those
>scenarios.
>>> >> >> >> >
>>> >> >> >> >v3: Fixed a fumble with compilation.
>>> >> >> >>
>>> >> >> >> Hi Ville,
>>> >> >> >> Can I keep your RB on this version. We have a clean CI
>>> >> >> >> result available
>>now.
>>> >> >> >
>>> >> >> >I'm confused. Why didn't disabling degamma+gamma work?
>>> >> >>
>>> >> >> We need to disable degamma/gamma and also make sure we don't
>>> >> >> set them again with linear values, which was being done currently.
>>> >> >> Hence, disabled it and later made sure it's kept at that.
>>> >> >
>>> >> >Who is turning it back on and why?
>>> >>
>>> >> When we call disable from IGT, it passes a NULL LUT. In this case,
>>> >> default linear LUT is getting applied in kernel. I am not sure if
>>> >> we really disable the gamma/degamma fully in driver. It just works
>>> >> with linear values
>>> >and remains enabled.
>>> >
>>> >We would disable after
>>> >https://patchwork.freedesktop.org/series/58137/
>>> >
>>> >Hmm. Looks like one patch missing r-b. I should probably go respin
>>> >that with Matt's comment added.
>>>
>>> Ok sure, will re-test the patch once your change is merged and update the test.
>>Thanks.
>>
>>Merged now. Though on GLK the kernel still has to load a linear degamma
>>ramp whenever the csc is used since the two are enabled/disabled by the same bit.
>
>Thanks Ville. Will re-try the test and get back.

I have tested and it seems just disabling gamma/degamma is enough after your recent changes.
I will update the test and float the next revised version.

>Regards,
>Uma Shankar
>
>>--
>>Ville Syrjälä
>>Intel
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