linux-kernel - Re: [PATCH v5 0/4] drm: Minimum backlight overrides and implementation for amdgpu

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Message-ID: <1dc9ac27-1447-435d-99d8-9c4cf5a42090@t-8ch.de>
Date: Thu, 22 Aug 2024 08:09:55 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Alex Deucher <alexander.deucher@....com>, 
	Christian König <christian.koenig@....com>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>, 
	Rodrigo Siqueira <Rodrigo.Siqueira@....com>, Matt Hartley <matt.hartley@...il.com>, 
	Kieran Levin <ktl@...mework.net>, Hans de Goede <hdegoede@...hat.com>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, Xinhui Pan <Xinhui.Pan@....com>, 
	Jonathan Corbet <corbet@....net>, amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Dustin Howett <dustin@...ett.net>, linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 0/4] drm: Minimum backlight overrides and
 implementation for amdgpu

Hi Mario,

(+ a question for Dustin inside)

On 2024-08-21 15:45:46+0000, Mario Limonciello wrote:
> On 8/18/2024 01:56, Thomas Weißschuh wrote:
> > The value of "min_input_signal" returned from ATIF on a Framework AMD 13
> > is "12". This leads to a fairly bright minimum display backlight.
> > 
> > Introduce a quirk to override "min_input_signal" to "0" which leads to a
> > much lower minimum brightness, which is still readable even in daylight.
> > 
> 
> Apologies for my delayed response, I've been OOO a while.

Welcome back!

> An earlier version of this series I had asked if this could be tested
> specifically with panel_power_savings enabled to ensure we're not causing a
> regression with such a low minimum and panel power savings turned up to the
> maximum.  If such a dependency does exist, I believe panel power savings
> will need to get an extra check introduced to disable it when the brightness
> falls below the previous threshold that was programmed by the firmware.
> 
> Did that ever get checked?

No, I forgot to check that. Sorry about that.
I'll check it for v6.
Dustin, maybe you could also test this on the other panels?

> > Tested on a Framework AMD 13 BIOS 3.05 and Framework AMD 16.
> > 
> 
> As far as I can tell this series doesn't apply any quirks to Framework 16.
> So by testing, do you mean that you tested that it didn't cause regressions
> (which it shouldn't; the panels don't match!).

This is a leftover from an earlier revision, which applied to all
Framework devices. I'll drop it.

> 
> > One solution would be a fixed firmware version, which was announced but
> > has no timeline. >
> > ---
> > Changes in v5:
> > - Forward-declare struct drm_edid
> > - Reorder patches, quirk entries are last
> > - Add patch from Dustin for additional quirk entries
> > - Link to v4: https://lore.kernel.org/r/20240812-amdgpu-min-backlight-quirk-v4-0-56a63ff897b7@weissschuh.net
> > 
> > Changes in v4:
> > - Switch back to v2 implementation
> > - Add MODULE_DESCRIPTION()
> > - Simplify quirk infrastructure to only handle min backlight quirks.
> >    It can be extended if necessary.
> > - Expand documentation.
> > - Link to v3: https://lore.kernel.org/r/20240731-amdgpu-min-backlight-quirk-v3-0-46d40bb21a62@weissschuh.net
> > 
> > Changes in v3:
> > - Switch to cmdline override parameter
> > - Link to v2: https://lore.kernel.org/r/20240623-amdgpu-min-backlight-quirk-v2-0-cecf7f49da9b@weissschuh.net
> > 
> > Changes in v2:
> > - Introduce proper drm backlight quirk infrastructure
> > - Quirk by EDID and DMI instead of only DMI
> > - Limit quirk to only single Framework 13 matte panel
> > - Link to v1: https://lore.kernel.org/r/20240610-amdgpu-min-backlight-quirk-v1-1-8459895a5b2a@weissschuh.net
> > 
> > ---
> > Dustin L. Howett (1):
> >        drm: panel-backlight-quirks: Add Framework 13 glossy and 2.8k panels
> > 
> > Thomas Weißschuh (3):
> >        drm: Add panel backlight quirks
> >        drm/amd/display: Add support for minimum backlight quirk
> >        drm: panel-backlight-quirks: Add Framework 13 matte panel
> > 
> >   Documentation/gpu/drm-kms-helpers.rst             |  3 +
> >   drivers/gpu/drm/Kconfig                           |  4 +
> >   drivers/gpu/drm/Makefile                          |  1 +
> >   drivers/gpu/drm/amd/amdgpu/Kconfig                |  1 +
> >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++
> >   drivers/gpu/drm/drm_panel_backlight_quirks.c      | 94 +++++++++++++++++++++++
> >   include/drm/drm_utils.h                           |  4 +
> >   7 files changed, 117 insertions(+)
> > ---
> > base-commit: c3f2d783a459980eafd24c5af94ccd56a615961f
> > change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
> > 
> > Best regards,
>