Re: [PATCH RFC 3/3] drm/amd/display: Warn about an invalid ATIF backlight signal range

[Ray Wu <ray.wu@amd.com>]

Reviewed-by: Ray Wu <ray.wu@amd.com>

On 11/4/2026 6:31 PM, Hugo Sales wrote:
> 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@hsal.es>
> ---
>   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;
>   	}
>   
>