[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20210715121002.32fa8e1d@eldfell>
Date: Thu, 15 Jul 2021 12:10:02 +0300
From: Pekka Paalanen <ppaalanen@...il.com>
To: Werner Sembach <wse@...edocomputers.com>
Cc: sunpeng.li@....com, intel-gfx@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
airlied@...ux.ie, amd-gfx@...ts.freedesktop.org,
tzimmermann@...e.de, rodrigo.vivi@...el.com,
alexander.deucher@....com, christian.koenig@....com
Subject: Re: [PATCH v4 03/17] drm/uAPI: Add "active bpc" as feedback channel
for "max bpc" drm property
On Wed, 14 Jul 2021 20:18:57 +0200
Werner Sembach <wse@...edocomputers.com> wrote:
> Am 01.07.21 um 13:30 schrieb Werner Sembach:
> > Am 01.07.21 um 09:42 schrieb Pekka Paalanen:
> >> On Wed, 30 Jun 2021 11:42:10 +0200
> >> Werner Sembach <wse@...edocomputers.com> wrote:
> >>
> >>> Am 30.06.21 um 10:21 schrieb Pekka Paalanen:
> >>>> On Tue, 29 Jun 2021 13:02:05 +0200
> >>>> Werner Sembach <wse@...edocomputers.com> wrote:
> >>>>
> >>>>> Am 28.06.21 um 19:03 schrieb Werner Sembach:
> >>>>>> Am 18.06.21 um 11:11 schrieb Werner Sembach:
> >>>>>>> Add a new general drm property "active bpc" which can be used by graphic
> >>>>>>> drivers to report the applied bit depth per pixel back to userspace.
> >>>>>>>
> >>>>>>> While "max bpc" can be used to change the color depth, there was no way to
> >>>>>>> check which one actually got used. While in theory the driver chooses the
> >>>>>>> best/highest color depth within the max bpc setting a user might not be
> >>>>>>> fully aware what his hardware is or isn't capable off. This is meant as a
> >>>>>>> quick way to double check the setup.
> >>>>>>>
> >>>>>>> In the future, automatic color calibration for screens might also depend on
> >>>>>>> this information being available.
> >>>>>>>
> >>>>>>> Signed-off-by: Werner Sembach <wse@...edocomputers.com>
> >>>>>>> ---
> >>>>>>> drivers/gpu/drm/drm_connector.c | 51 +++++++++++++++++++++++++++++++++
> >>>>>>> include/drm/drm_connector.h | 8 ++++++
> >>>>>>> 2 files changed, 59 insertions(+)
> New idea: Instead of the "active"-properties with various if cases in
> the kernel code, there could just be blob properties exposing the hdmi
> infoframes, hdmi general control packages, dp misc0 and misc1 and dp vsc
> sdp.
>
> Combined they have all the color information and it is made sure that
> it's what is actually send to the monitor (I would consider sending
> something differed then what is told in the infoframes a bug).
>
> They also have built in version numbers, if in the future they contain
> more information.
>
> Only disadvantage: We leave parsing for human readable output to the
> userspace.
>
> Alternatively keep the "active"-properties but fill them from the
> infoframes.
>
> I'm not entirely sure where to do that on amd, because there the
> infoframes are directly created in the dc code shortly before writing
> them to the hardware registers and immediately forgotten afterwards. But
> you still have access to the connector struct from that code so the
> property could be updated directly there.
>
Hi,
I'm not fundamentally against that as long as we have a common
userspace library to parse those blobs. In libdrm perhaps? Or a new
library?
But I also don't know about the technical feasibility, is it a good
idea.
OTOH, that could be the best thing for testing drivers vs. KMS UAPI
when you don't have a hardware HDMI/DP grabber to inspect the
infoframes. So maybe kernel CI would like that?
Thanks,
pq
Content of type "application/pgp-signature" skipped
Powered by blists - more mailing lists