linux-kernel - [PATCH v2 0/5] drm: panel-backlight-quirks: Do partial refactor and apply OLED fix

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Message-ID: <20250827174400.3692549-1-lkml@antheas.dev>
Date: Wed, 27 Aug 2025 19:43:55 +0200
From: Antheas Kapenekakis <lkml@...heas.dev>
To: amd-gfx@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	philm@...jaro.org,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Mario Limonciello <mario.limonciello@....com>,
	Robert Beckett <bob.beckett@...labora.com>,
	Antheas Kapenekakis <lkml@...heas.dev>
Subject: [PATCH v2 0/5] drm: panel-backlight-quirks: Do partial refactor and
 apply OLED fix

This is an alternative to [1], since Phil found out there are still invalid
values. We need to reconsider the other patch in that series anyway because
the latest AMD firmware update might have fixed the Z13.

This series refactors the panel-backlight-quirks code to make it easier to
add new quirks. Specifically, it adds the ability to bind to a secondary
DMI match so that the make of a device can be specified. Then, it makes
EDID optional, for devices we know the value should be applied universally.

This is then used to add a quirk for OLED panels that have an issue
when their backlight is set with a value that contains a 0/1 value in their
minor byte. This issue affects four handhelds from three different vendors,
three of which are in the field. This quirk applies a |3 mask to the
backlight value, which avoids this issue. In addition, the value change
is minor enough so that it is essentially a NOOP. There is no need for
ensuring it runs only on panels with faulty firmwares.

Finally, since allowed by this refactor, a quirk for Steam Decks is added
that lowers their minimum brightness to 0, matching SteamOS. This is
a nicety commit, which allows for mildly lower minimum brightness, so
there is no time sensitivity for having it merged. Mario noted that if
that quirk was refactored to use an EDID match via the current interface,
it could go through the fixes tree and land sooner, but perhaps it is not
worth the effort.

[1] https://lore.kernel.org/all/20250824085351.454619-2-lkml@antheas.dev/

---
V1: https://lore.kernel.org/all/20250824200202.1744335-1-lkml@antheas.dev/

Changes since v1:
- Remove leftover quirk from patch 3 (refactor)
- Add dangling comma in patch 4 (oled quirk)
- Add the next generation Zotac Zone in patch 4 (currently unreleased)
- Reword patch 1 and 5 subjects

Antheas Kapenekakis (5):
  drm: panel-backlight-quirks: Make EDID match optional
  drm: panel-backlight-quirks: Convert brightness quirk to generic
    structure
  drm: panel-backlight-quirks: Add secondary DMI match
  drm: panel-backlight-quirks: Add brightness mask quirk
  drm: panel-backlight-quirks: Add Steam Deck brightness quirk

 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  19 ++-
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |   6 +
 drivers/gpu/drm/drm_panel_backlight_quirks.c  | 113 ++++++++++++++----
 include/drm/drm_utils.h                       |   8 +-
 4 files changed, 115 insertions(+), 31 deletions(-)

base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
-- 
2.51.0