linux-kernel - [PATCH v3 0/2] drm: minimum backlight overrides and implementation for amdgpu

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Message-Id: <20240731-amdgpu-min-backlight-quirk-v3-0-46d40bb21a62@weissschuh.net>
Date: Wed, 31 Jul 2024 19:00:45 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: 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>, 
 Mario Limonciello <mario.limonciello@....com>, 
 Matt Hartley <matt.hartley@...il.com>, Kieran Levin <ktl@...mework.net>, 
 Hans de Goede <hdegoede@...hat.com>, Xinhui Pan <Xinhui.Pan@....com>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, 
 linux-kernel@...r.kernel.org, Dustin Howett <dustin@...ett.net>, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v3 0/2] drm: minimum backlight overrides and implementation
 for amdgpu

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.

Add a generic override helper for the user to override the settings
provided by the firmware through the kernel cmdline.
Also add amdgpu as a user of that helper.

One solution would be a fixed firmware version, which was announced but
has no timeline.

This helper does conflict with the mode override via the cmdline.
Only one can be specified.
IMO the mode override can be extended to also handle "min-brightness"
when that becomes necessary.

---
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

---
Thomas Weißschuh (2):
      drm/connector: add drm_connector_get_cmdline_min_brightness_override()
      drm/amd/display: implement minimum brightness override

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
 drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
 include/drm/drm_connector.h                       |  2 ++
 3 files changed, 42 insertions(+)
---
base-commit: 36821612eb3091a21f7f4a907b497064725080c3
change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>