Re: [igt-dev] [PATCH i-g-t v2 1/2] kms_hdr: Skip HDR tests on pre-Kaby Lake Intel devices

["Shankar, Uma" <uma.shankar@intel.com>]

> -----Original Message-----
> From: Latvala, Petri <petri.latvala@intel.com>
> Sent: Tuesday, March 9, 2021 7:32 PM
> To: Jeremy Cline <jcline@redhat.com>
> Cc: Sharma, Swati2 <swati2.sharma@intel.com>; Maarten Lankhorst
> <maarten.lankhorst@linux.intel.com>; igt-dev@lists.freedesktop.org; Shankar, Uma
> <uma.shankar@intel.com>
> Subject: Re: [igt-dev] [PATCH i-g-t v2 1/2] kms_hdr: Skip HDR tests on pre-Kaby Lake
> Intel devices
> 
> On Mon, Mar 08, 2021 at 10:06:59AM -0500, Jeremy Cline wrote:
> > On Mon, Mar 08, 2021 at 02:53:39PM +0200, Petri Latvala wrote:
> > > On Mon, Mar 08, 2021 at 06:11:09PM +0530, Sharma, Swati2 wrote:
> > > >
> > > >
> > > > On 08-Mar-21 2:17 PM, Petri Latvala wrote:
> > > > > On Fri, Mar 05, 2021 at 11:42:52AM -0500, Jeremy Cline wrote:
> > > > > > According to the Intel documentation[0] I could find, HDR
> > > > > > support is only in Kaby Lake+. Skip tests in kms_hdr if the
> > > > > > hardware doesn't support HDR.
> > > > > >
> > > > > > [0]
> > > > > > https://www.intel.com/content/dam/support/us/en/documents/grap
> > > > > > hics/HDR_Intel_Graphics_TechWhitePaper.pdf
> > > > > >
> > > > > > Signed-off-by: Jeremy Cline <jcline@redhat.com>
> > > > >
> > > > >
> > > > > While that might be true, strictly speaking IGT tests are not
> > > > > testing the HW capabilities but the kernel interfaces. The
> > > > > difference is often only interesting for nitpicking.
> > > > >
> > > > > However, in this case a good argument can be made either way,
> > > > > with what the correct behaviour with setting the "max bpc"
> > > > > property when the HW doesn't support HDR _output_ should be. IGT
> > > > > tests should be written the way one would expect "real"
> > > > > userspace to behave; does the documented kernel interface
> > > > > require userspace to detect the device id somehow? The connector
> > > > > property is there so one would assume setting it should work and do
> something.
> > > > >
> > > > > A good argument can also be made that even though we're testing
> > > > > "just the interface", we (Intel) should have a separate test
> > > > > that requires actual HW support...
> > > > >
> > > > > Swati, Maarten, thoughts on this? Are we even testing the right
> > > > > things for i915 at all? Are we able to express the HW
> > > > > requirement for HDR with something other than comparing devid?
> > > > > Should we? (If we should not, please suggest a better way to get
> > > > > around the issue being fixed
> > > > > here)
> > > >
> > > > There are 2 types of tests which are being validated in kms_hdr
> > > > (i) bpc switch
> > > > (ii) hdr metadata
> > > > And both these tests will skip on platforms which doesn't support
> > > > respective connector properties (MAX_BPC, HDR_OUTPUT_METADATA
> > > > resp). These tests are independent of platforms on which they are
> > > > being tested.
> > > > This can be validated from the link below:
> > > > https://intel-gfx-ci.01.org/tree/drm-tip/shards-all.html?testfilte
> > > > r=kms_hdr where you can see platforms which doesn't support either
> > > > max_bpc or hdr_metadata connector properties; tests are being
> > > > skipped.
> > > >
> > > > And I don't think anything is being fixed here
> > >
> > > What I meant is the fix in patch 2, removing the removal of the
> > > primary plane, which was done because of a HSW limitation. Patch 1
> > > (this thread) is then making sure HSW is unaffected by a spurious
> > > failure. Sorry for not being clear when pulling more CCs.
> > >
> >
> > There are definitely finer-grain ways to do this, but this "works" so
> > I figured it'd be good to start here and have a discussion about it.
> >
> > One option would be to just wrap the plane-removal call in a device
> > check. Another would be to try and find a plane size that meets
> > whatever the scaling requirements are for hsw (assuming there's
> > overlap between the conflicting requirements of hardware).
> >
> > I don't have a strong opinion about where the checks happen, it seems
> > like a trade-off between in-test complexity and the breadth of the
> > test matrix, and I can't say how useful it is to make sure the MAX_BPC
> > interface works on a specific generation of hardware. I'm happy to do
> > either of those options (or another option I've not considered),
> > whatever you folks think is the best trade-off.
> 
> 
> Checked how HSW actually behaves with this and
> 
> https://intel-gfx-ci.01.org/tree/drm-tip/TrybotIGT_300/shard-
> hsw4/igt@kms_hdr@bpc-switch.html
> 
> Swati, what's your opinion? if (amdgpudevice) around the plane removal or what's
> best here?

Hi Petri,
I feel limiting it to amdgpudevice seems a safer and easier route here without disturbing the legacy behavior.

Regards,
Uma Shankar

> 
> 
> --
> Petri Latvala
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