linux-kernel - Re: [PATCH] drm: DON'T require each CRTC to have a unique primary plane

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Message-Id: <7BLQQQ.ZY1PEPCLZS2L2@crapouillou.net>
Date:   Mon, 29 Mar 2021 16:21:07 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Pekka Paalanen <ppaalanen@...il.com>
Cc:     Simon Ser <contact@...rsion.fr>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
        od@...c.me, dri-devel@...ts.freedesktop.org, stable@...r.kernel.org
Subject: Re: [PATCH] drm: DON'T require each CRTC to have a unique primary
 plane

Le lun. 29 mars 2021 à 17:35, Pekka Paalanen <ppaalanen@...il.com> a 
écrit :
> On Mon, 29 Mar 2021 12:41:00 +0100
> Paul Cercueil <paul@...pouillou.net> wrote:
> 
>>  Hi,
>> 
>>  Le lun. 29 mars 2021 à 11:15, Pekka Paalanen <ppaalanen@...il.com> 
>> a
>>  écrit :
>>  > On Sat, 27 Mar 2021 11:26:26 +0000
>>  > Paul Cercueil <paul@...pouillou.net> wrote:
>>  >
>>  >>  It has two mutually exclusive background planes (same Z level) 
>> + one
>>  >>  overlay plane.
>>  >
>>  > What's the difference between the two background planes?
>>  >
>>  > How will generic userspace know to pick the "right" one?
>> 
>>  First primary plane cannot scale, supports RGB and C8. Second 
>> primary
>>  plane goes through the IPU, and as such can scale and convert pixel
>>  formats; it supports RGB, non-planar YUV, and multi-planar YUV.
>> 
>>  Right now the userspace apps we have will simply pick the first one
>>  that fits the bill.
> 
> What would be the downside of exposing just one "virtual" primary
> plane, and then have the driver pick one of the two hardware planes as
> appropriate per modeset?

The IPU plane is in a different driver, so all the callbacks are 
different. That sounds like it would be a mess.

-Paul

> Thanks,
> pq
> 
>>  >>  Le sam. 27 mars 2021 à 11:24, Simon Ser <contact@...rsion.fr> a
>>  >> écrit
>>  >>  :
>>  >>  > On Saturday, March 27th, 2021 at 12:22 PM, Paul Cercueil
>>  >>  > <paul@...pouillou.net> wrote:
>>  >>  >
>>  >>  >>  The ingenic-drm driver has two mutually exclusive primary 
>> planes
>>  >>  >>  already; so the fact that a CRTC must have one and only one
>>  >> primary
>>  >>  >>  plane is an invalid assumption.
>>  >>  >
>>  >>  > Why does this driver expose two primary planes, if it only 
>> has a
>>  >>  > single
>>  >>  > CRTC?
>>  >>
>>  >>
>>  >>  _______________________________________________
>>  >>  dri-devel mailing list
>>  >>  dri-devel@...ts.freedesktop.org
>>  >>  https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>  >
>> 
>> 
> 

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