From: Simon Ser <contact@emersion.fr>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Sebastian Wick <sebastian.wick@redhat.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Martin Roukala <martin.roukala@mupuf.org>,
Christoph Grenz <christophg+lkml@grenz-bonn.de>,
wayland <wayland-devel@lists.freedesktop.org>,
Yusuf Khan <yusisamerican@gmail.com>
Subject: Re: [RFC] drm/kms: control display brightness through drm_connector properties
Date: Fri, 29 Apr 2022 08:59:24 +0000 [thread overview]
Message-ID: <vdb4oRbKTPYjAGPcmjKfhcDQbMb1VuiJwF99I3UwkwUAsyEvvq5x7yKdP0mx5tEeNc2idU_qBSlbMM4dlv7apLeDvG3PIAkvRMjwVNKZGCk=@emersion.fr> (raw)
In-Reply-To: <0f8e771c-bf0d-f20b-50da-dc84f760ff82@redhat.com>
On Friday, April 29th, 2022 at 10:55, Hans de Goede <hdegoede@redhat.com> wrote:
> I believe that we can fix the new interface, the plan is for there
> to be some helper code to proxy the new connector properties to what
> is still a good old backlight-device internally in the kernel,.
>
> This proxy-ing code could take a minimum value below which it should
> not go when things are set through the properties and then if e.g.
> the /sys/class/backlight interface offers range of 0-65535 and the
> kms driver asks the proxying helper for a minimum of 500, show this
> as 0-65035 on the property, simply adding 500 before sending the
> value to the backlight-device on writes (and subtracting 500 on reads,
> clamping to 0 as lowest value reported on reads).
>
> This way apps using the new API can never go below 500 (in this
> example) and for old API users nothing changes.
>
> Given that Jani seems to be in favor of enforcing some minimal value
> inside the i915 code going forward and also what Alex said that the
> amdgpu code already enforces its own minimum if the video BIOS tables
> don't provide one, it seems that there is consensus that we want 0
> to mean minimum brightness at which the screen is still somewhat
> readable and that we want to enforce this at the kernel level.
>
> Which also means the weird hint property which I came up with won't
> be necessary as we now have a clean definition of what brightness
> 0 is supposed to mean (in the new API) and any cases where this is not
> the case are kernel bugs and should be fixed in the kernel.
Looks like a good approach to me from user-space PoV!
next prev parent reply other threads:[~2022-04-29 8:59 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 15:38 [RFC] drm/kms: control display brightness through drm_connector properties Hans de Goede
2022-04-07 16:51 ` Simon Ser
2022-04-07 17:43 ` Hans de Goede
2022-04-07 21:05 ` Alex Deucher
2022-04-08 8:07 ` Daniel Vetter
2022-04-08 9:58 ` Hans de Goede
2022-04-08 10:09 ` Hans de Goede
2022-04-08 10:16 ` Simon Ser
2022-04-08 10:26 ` Hans de Goede
2022-04-13 8:32 ` Daniel Vetter
2022-04-13 8:38 ` Simon Ser
2022-04-13 9:44 ` Hans de Goede
2022-04-08 10:23 ` Hans de Goede
2022-04-08 14:08 ` Alex Deucher
2022-04-08 14:55 ` Hans de Goede
2022-04-08 15:11 ` Alex Deucher
2022-04-11 10:18 ` Hans de Goede
2022-04-11 11:34 ` Pekka Paalanen
2022-04-11 11:50 ` Hans de Goede
2022-04-11 13:11 ` Mikhail Gusarov
2022-04-11 14:11 ` Alex Deucher
2022-04-14 10:24 ` Jani Nikula
2022-04-27 14:03 ` Daniel Vetter
2022-04-27 14:23 ` Jani Nikula
2022-04-27 14:26 ` Daniel Vetter
2022-04-29 8:55 ` Hans de Goede
2022-04-29 8:59 ` Simon Ser [this message]
2022-04-29 9:06 ` Pekka Paalanen
2022-04-29 9:49 ` Lattannavar, Sameer
2022-04-08 8:22 ` Simon Ser
2022-04-08 15:00 ` Hans de Goede
2022-04-11 10:35 ` Hans de Goede
2022-04-07 18:58 ` Carsten Haitzler
2022-04-11 10:27 ` Hans de Goede
2022-04-11 11:14 ` Carsten Haitzler
2022-04-14 13:10 ` Jani Nikula
2022-05-18 12:59 ` Hans de Goede
2022-05-18 14:23 ` Jani Nikula
2022-05-31 10:40 ` Hans de Goede
2022-05-18 14:40 ` Ville Syrjälä
2022-08-24 2:18 ` Yusuf Khan
2022-08-25 8:27 ` Hans de Goede
2022-08-25 21:40 ` Yusuf Khan
2022-08-28 8:08 ` Hans de Goede
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='vdb4oRbKTPYjAGPcmjKfhcDQbMb1VuiJwF99I3UwkwUAsyEvvq5x7yKdP0mx5tEeNc2idU_qBSlbMM4dlv7apLeDvG3PIAkvRMjwVNKZGCk=@emersion.fr' \
--to=contact@emersion.fr \
--cc=christophg+lkml@grenz-bonn.de \
--cc=dri-devel@lists.freedesktop.org \
--cc=hdegoede@redhat.com \
--cc=martin.roukala@mupuf.org \
--cc=sebastian.wick@redhat.com \
--cc=wayland-devel@lists.freedesktop.org \
--cc=yusisamerican@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).