[PATCH RFC 3/3] drm/amd/display: Warn about an invalid ATIF backlight signal range
From: Hugo Sales
Date: Wed Nov 04 2026 - 05:31:28 EST
When the ATIF signal range is out of bounds or narrower than
AMDGPU_DM_MIN_SPREAD, amdgpu_dm_validate_backlight_caps() drops the
firmware caps and the driver falls back to a range of 12-255. It only
says so with drm_dbg_kms(), so a user whose brightness range changed
finds nothing in dmesg to report
Make it a drm_warn() with FW_BUG, like the custom curve warnings
Signed-off-by: Hugo Sales <hugo@xxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
index 3a27fb956627a..68b34654fca02 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
@@ -104,8 +104,10 @@ void amdgpu_dm_validate_backlight_caps(struct amdgpu_display_manager *dm, int bl
caps->min_input_signal < 0 ||
spread > AMDGPU_DM_DEFAULT_MAX_BACKLIGHT ||
spread < AMDGPU_DM_MIN_SPREAD) {
- drm_dbg_kms(adev_to_drm(dm->adev), "DM: Invalid backlight caps: min=%d, max=%d\n",
- caps->min_input_signal, caps->max_input_signal);
+ drm_warn(adev_to_drm(dm->adev), FW_BUG
+ "ATIF: backlight signal range %d to %d is invalid, using %d to %d\n",
+ caps->min_input_signal, caps->max_input_signal,
+ AMDGPU_DM_DEFAULT_MIN_BACKLIGHT, AMDGPU_DM_DEFAULT_MAX_BACKLIGHT);
caps->caps_valid = false;
}
--
2.56.0