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

[Ville Syrjälä]

On Wed, Mar 27, 2019 at 01:37:31PM +0000, Shankar, Uma wrote:
> 
> 
> >-----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.

-- 
Ville Syrjälä
Intel