[PATCH] Revert "drm/amd/display: Fix AMDGPU_MAX_BL_LEVEL value"

[Limonciello, Mario]

On 7/21/25 8:43 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello at amd.com>
> 
> This reverts commit 66abb996999de0d440a02583a6e70c2c24deab45.
> This broke custom brightness curves but it wasn't obvious because
> of other related changes. Custom brightness curves are always
> from a 0-255 input signal. The correct fix was to fix the default
> value which was done by [1].
> 
> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4412
> Cc: stable at vger.kernel.org
> Link: https://lore.kernel.org/amd-gfx/0f094c4b-d2a3-42cd-824c-dc2858a5618d@kernel.org/T/#m69f875a7e69aa22df3370b3e3a9e69f4a61fdaf2
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> 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 8e1405e9025ba..f3e407f31de11 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4740,16 +4740,16 @@ static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
>   	return 1;
>   }
>   
> -/* Rescale from [min..max] to [0..MAX_BACKLIGHT_LEVEL] */
> +/* Rescale from [min..max] to [0..AMDGPU_MAX_BL_LEVEL] */
>   static inline u32 scale_input_to_fw(int min, int max, u64 input)
>   {
> -	return DIV_ROUND_CLOSEST_ULL(input * MAX_BACKLIGHT_LEVEL, max - min);
> +	return DIV_ROUND_CLOSEST_ULL(input * AMDGPU_MAX_BL_LEVEL, max - min);
>   }
>   
> -/* Rescale from [0..MAX_BACKLIGHT_LEVEL] to [min..max] */
> +/* Rescale from [0..AMDGPU_MAX_BL_LEVEL] to [min..max] */
>   static inline u32 scale_fw_to_input(int min, int max, u64 input)
>   {
> -	return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), MAX_BACKLIGHT_LEVEL);
> +	return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), AMDGPU_MAX_BL_LEVEL);
>   }
>   
>   static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *caps,
> @@ -4977,7 +4977,7 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
>   		drm_dbg(drm, "Backlight caps: min: %d, max: %d, ac %d, dc %d\n", min, max,
>   			caps->ac_level, caps->dc_level);
>   	} else
> -		props.brightness = props.max_brightness = MAX_BACKLIGHT_LEVEL;
> +		props.brightness = props.max_brightness = AMDGPU_MAX_BL_LEVEL;

This bottom hunk doesn't need to revert, that one is fine.  The other 
two need to be reverted though to fix this issue.