From 36d63ce5dbc0dc37b5af90f6b7c3b92ab26403b7 Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Fri, 28 Feb 2025 12:51:45 -0600
Subject: [PATCH] drm/amd/display: Add a new dcdebugmask to allow turning off
brightness curve
Upgrading the kernel may cause some systems that were previously not using
a firmware specified brightness curve to use one.
In the event of problems with this curve (for example an interpolation
error) add a new dcdebugmask value that can be used to turn it off. Also
add an info message to show that custom brightness curves are currently in
use.
Reviewed-by: Alex Hung <alex.hung@amd.com>
Link: https://lore.kernel.org/r/20250228185145.186319-6-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++++
drivers/gpu/drm/amd/include/amd_shared.h | 4 ++++
2 files changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 5e049b8f877dc..58848d6b475a6 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4758,6 +4758,9 @@ static u32 convert_brightness_from_user(const struct amdgpu_dm_backlight_caps *c
for (int i = 0; i < caps->data_points; i++) {
u8 signal, lum;
+ if (amdgpu_dc_debug_mask & DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE)
+ break;
+
signal = caps->luminance_data[i].input_signal;
lum = caps->luminance_data[i].luminance;
@@ -4942,6 +4945,8 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
} else
props.brightness = AMDGPU_MAX_BL_LEVEL;
+ if (caps.data_points && !(amdgpu_dc_debug_mask & DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE))
+ drm_info(drm, "Using custom brightness curve\n");
props.max_brightness = AMDGPU_MAX_BL_LEVEL;
props.type = BACKLIGHT_RAW;
diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h
index c0538763ec1ad..485b713cfad0a 100644
--- a/drivers/gpu/drm/amd/include/amd_shared.h
+++ b/drivers/gpu/drm/amd/include/amd_shared.h
@@ -354,6 +354,10 @@ enum DC_DEBUG_MASK {
* @DC_DISABLE_SUBVP: If set, disable DCN Sub-Viewport feature in amdgpu driver.
*/
DC_DISABLE_SUBVP = 0x20000,
+ /**
+ * @DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE: If set, disable support for custom brightness curves
+ */
+ DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE = 0x40000,
};
enum amd_dpm_forced_level;
--
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