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Subject: Re: [PATCH v4 01/10] drm/fourcc: Add AFBC yuv fourccs for Mali
To:     Brian Starkey <Brian.Starkey@arm.com>
Cc:     Ayan Halder <Ayan.Halder@arm.com>,
        Liviu Dudau <Liviu.Dudau@arm.com>,
        "malidp@foss.arm.com" <malidp@foss.arm.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "alyssa@rosenzweig.io" <alyssa@rosenzweig.io>, nd <nd@arm.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Dave Airlie <airlied@gmail.com>,
        Swati Sharma <swati2.sharma@intel.com>,
        Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>,
        Vidya Srinivas <vidya.srinivas@intel.com>
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From:   Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Message-ID: <a67ec415-af2b-9ddd-9856-b5066ce2b791@linux.intel.com>
Date:   Mon, 18 Mar 2019 19:12:24 +0100
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Op 18-03-2019 om 16:40 schreef Brian Starkey:
> Hi,
>
> On Mon, Mar 18, 2019 at 11:17:55AM +0100, Maarten Lankhorst wrote:
>
> <snip>
>
>> Hey..
>>
>> There's a conflict with this patch and the merge of topic/hdr-formats, resulting in double definitions for Y210, Y410 and P010.
>>
>> Worse still is that one has set has_alpha to true for Y41x and other to false.
>>
>> ~Maarten
>>
> Oh that's sad :-( I think this fell through the cracks on our side
> when someone left our team. Also turns out I'm not subscribed to
> igt-dev.
>
> I see you commented the same on one of the previous patches, and that
> there was some discussion of this on the test patches too.
>
> I have been referring to Microsoft's page[1] as "the" source for these
> formats, which does indeed call out Y410 as having 2 bits of alpha.
> Our GPU expects alpha.

Ah. Yeah there has been discussion on whether there was supposed to be alpha or not, but the original discussion on HDR formats has been completely ignored by arm.

The patch had originally a few arm devs on cc and was sent to dri-devel with linux-media cc'd. Was sad to see it completely ignored so after having been sent twice I pushed it.

> Was there a specific reason for opting to change the test instead of
> the definition? Any way to get this changed now?
>
> It doesn't seem that sensible for the kernel to call something Y410
> which doesn't match an "existing" definition by the same name. If
> alpha needs to be ignored on scanout, the alpha blend mode property
> can be used (more archaeology - I see that was still giving CRC
> failures, but that might be a "known issue" for all YUV on your HW?)

Were a few bugs, but should be fixed now. :)

Well only that we didn't have hw supporting alpha, and didn't hear back from others so we went without alpha.

> -Brian
>
> [1] https://docs.microsoft.com/en-us/windows/desktop/medfound/10-bit-and-16-bit-yuv-video-formats#444-formats