linux-kernel - [PATCH 1/3] drm: panel-backlight-quirks: Add quirk to disable custom brightness curve

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Message-ID: <20251221192422.2726883-2-samuel@dionne-riel.com>
Date: Sun, 21 Dec 2025 14:24:18 -0500
From: Samuel Dionne-Riel <samuel@...nne-riel.com>
To: 
Cc: Samuel Dionne-Riel <samuel@...nne-riel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] drm: panel-backlight-quirks: Add quirk to disable custom brightness curve

While unverified, through observation it seems that some AMD GPU
devices' firmware provides default brightness curves that are not
adapted to the specific device.

When those curves are enabled, the resulting brightness control is much
less granular than the hardware supports.

On the specific device this was observed, this especially affected the
lowest range of brightness value, where no nuance existed.

This change results in a much smoother brightness curve at lower values,
with no observable drawbacks. This was used while also setting the
minimum backlight to (effectively) zero.

Signed-off-by: Samuel Dionne-Riel <samuel@...nne-riel.com>
---
 include/drm/drm_utils.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/drm/drm_utils.h b/include/drm/drm_utils.h
index 6a46f755daba0..28321e84bf2f8 100644
--- a/include/drm/drm_utils.h
+++ b/include/drm/drm_utils.h
@@ -19,6 +19,7 @@ int drm_get_panel_orientation_quirk(int width, int height);
 struct drm_panel_backlight_quirk {
 	u16 min_brightness;
 	u32 brightness_mask;
+	bool disable_custom_brightness_curve;
 };

 const struct drm_panel_backlight_quirk *
-- 
2.51.0