From: Eric Anholt <eric@anholt.net>
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/3] drm/vc4: Force ->x_scaling[1] should never be set to VC4_SCALING_NONE
Date: Thu, 08 Nov 2018 07:12:37 -0800 [thread overview]
Message-ID: <87sh0bob6i.fsf@anholt.net> (raw)
In-Reply-To: <20181108155659.7039c04f@bbrezillon>
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Boris Brezillon <boris.brezillon@bootlin.com> writes:
> On Thu, 08 Nov 2018 06:52:44 -0800
> Eric Anholt <eric@anholt.net> wrote:
>
>> Boris Brezillon <boris.brezillon@bootlin.com> writes:
>>
>> > For the YUV conversion to work properly, ->x_scaling[0,1] should never
>> > be set to VC4_SCALING_NONE, but vc4_get_scaling_mode() might return
>> > VC4_SCALING_NONE if the horizontal scaling ratio exactly matches the
>> > horizontal subsampling factor. Add a test to turn VC4_SCALING_NONE
>> > into VC4_SCALING_PPF when that happens.
>> >
>> > Fixes: fc04023fafec ("drm/vc4: Add support for YUV planes.")
>> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
>>
>> I couldn't find a spec justification for this -- did you have a testcase
>> that fails?
>
> Yep. Just set the downscaling ratio to 0.5 with an NV12 format and
> you'll hit the issue (I used modetest to do that):
>
> # modetest -M vc4 -s 29:1920x1080-60 -P 96@95:1920x1080*0.5@NV12
I found that the firmware has a similar behavior to your patch ("if Y is
!unity (x or scaling) and UV is unity, set UV to HPPF/VPPF scaling").
They also select the unity flag after the YUV scaling fixup.
Regardless, if this works, it's got my reviewed-by.
Hopefully we can do some IGT with writeback or chamelium testing all of
the X/Y scaling options with a focus on hitting these 1:1 ratios. The
state space is big and the docs are just ambiguous enough.
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next prev parent reply other threads:[~2018-11-08 15:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-24 10:05 [PATCH 1/3] drm/vc4: Set PPF scaling when the source image is only vertically scaled Boris Brezillon
2018-10-24 10:05 ` [PATCH 2/3] drm/vc4: Force ->x_scaling[1] should never be set to VC4_SCALING_NONE Boris Brezillon
2018-10-24 10:06 ` Boris Brezillon
2018-11-08 14:52 ` Eric Anholt
2018-11-08 14:56 ` Boris Brezillon
2018-11-08 15:12 ` Eric Anholt [this message]
2018-11-12 10:20 ` Dave Stevenson
2018-11-12 10:24 ` Boris Brezillon
2018-10-24 10:05 ` [PATCH 3/3] drm/vc4: Prefer PPF over TPZ when dst >= 2/3 src Boris Brezillon
2018-11-08 15:18 ` Eric Anholt
2018-10-24 15:02 ` [PATCH 1/3] drm/vc4: Set PPF scaling when the source image is only vertically scaled Boris Brezillon
2018-11-07 17:08 ` Eric Anholt
2018-11-08 9:41 ` Boris Brezillon
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