Question about CCS modifier on GLK

Question about CCS modifier on GLK

[Gabriel Krisman Bertazi]

Hi Ben and list folks,

I've been investigating some CI failures with the kms_ccs testcase in
the GLK hardware.  The original bug is linked below, but there are other
more basic tests failing when trying CCS on pipe C.

https://bugs.freedesktop.org/show_bug.cgi?id=104096

The reason for the failure is very straightforward, the function
skl_check_ccs_aux_surface() in intel_display.c rejects CCS modifiers for
PIPE_C, since that is not supported for SKL, KBL and as far as I can
tell APL as well.

But, since I don't have the specs for GLK yet (it's not available in
01.org), I can't tell if GLK will support it and the kernel must be
changed or if the testcase itself is bogus.  My money is on the later,
but I could use a confirmation before writing down the patch.

In short, does pipe C support render compression (ccs modifier) in glk?

Thanks,

-- 
Gabriel Krisman Bertazi
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Re: Question about CCS modifier on GLK

[Ville Syrjälä]

On Sun, Dec 17, 2017 at 10:45:13PM -0200, Gabriel Krisman Bertazi wrote:
> 
> Hi Ben and list folks,
> 
> I've been investigating some CI failures with the kms_ccs testcase in
> the GLK hardware.  The original bug is linked below, but there are other
> more basic tests failing when trying CCS on pipe C.
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=104096
> 
> The reason for the failure is very straightforward, the function
> skl_check_ccs_aux_surface() in intel_display.c rejects CCS modifiers for
> PIPE_C, since that is not supported for SKL, KBL and as far as I can
> tell APL as well.
> 
> But, since I don't have the specs for GLK yet (it's not available in
> 01.org), I can't tell if GLK will support it and the kernel must be
> changed or if the testcase itself is bogus.  My money is on the later,
> but I could use a confirmation before writing down the patch.
> 
> In short, does pipe C support render compression (ccs modifier) in glk?

No. But the current code is somewhat busted anyway. See
https://patchwork.freedesktop.org/series/29308/

-- 
Ville Syrjälä
Intel OTC
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Re: Question about CCS modifier on GLK

[Ben Widawsky]

On 17-12-17 22:45:13, Gabriel Krisman Bertazi wrote:
>
>Hi Ben and list folks,
>
>I've been investigating some CI failures with the kms_ccs testcase in
>the GLK hardware.  The original bug is linked below, but there are other
>more basic tests failing when trying CCS on pipe C.
>
>https://bugs.freedesktop.org/show_bug.cgi?id=104096
>
>The reason for the failure is very straightforward, the function
>skl_check_ccs_aux_surface() in intel_display.c rejects CCS modifiers for
>PIPE_C, since that is not supported for SKL, KBL and as far as I can
>tell APL as well.
>
>But, since I don't have the specs for GLK yet (it's not available in
>01.org), I can't tell if GLK will support it and the kernel must be
>changed or if the testcase itself is bogus.  My money is on the later,
>but I could use a confirmation before writing down the patch.
>
>In short, does pipe C support render compression (ccs modifier) in glk?
>
>Thanks,
>

The hardware almost certainly works, but it wasn't validated. So we should
probably just disable it, and I've reviewed your patch. As Ville pointed out,
the series which was merged wasn't quite right to begin with, and it'd be
helpful if you could review his patches to fix it up.

>-- 
>Gabriel Krisman Bertazi
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