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>

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 5e049b8f877dcee80d4bcb6deba774187f7f4169..58848d6b475a662b3e1d2d3a34317495f8f42e11 100644 (file)
--- 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 c0538763ec1ad1306378466e2b1eff40cf9664ec..485b713cfad0ac5526f0efb965a0729fec8c8bed 100644 (file)
--- 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;