[PATCH 07/17] drm/amd/display: Fix brightness level not retained over reboot

[Mario Limonciello]

On 11/1/2024 08:49, Zaeem Mohamed wrote:
> From: Tom Chung <chiahsuan.chung at amd.com>
> 
> [Why]
> During boot up and resume the DC layer will reset the panel
> brightness to fix a flicker issue.
> 
> It will cause the dm->actual_brightness is not the current panel
> brightness level. (the dm->brightness is the correct panel level)
> 
> [How]
> Set the backlight level after do the set mode.
> 
> Reviewed-by: Sun peng Li <sunpeng.li at amd.com>
> Signed-off-by: Tom Chung <chiahsuan.chung at amd.com>
> Signed-off-by: Zaeem Mohamed <zaeem.mohamed at amd.com>

Some more tags, please explicitly add these while merging.

Cc: stable at vger.kernel.org
Fixes: d9e865826c20 ("drm/amd/display: Simplify brightness initialization")
Reported-by: Mark Herbert <mark.herbert42 at gmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3655

> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 15 +++++++++++++++
>   1 file changed, 15 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 bbfc47f6595f..2599a99509de 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -9411,6 +9411,7 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
>   	bool mode_set_reset_required = false;
>   	u32 i;
>   	struct dc_commit_streams_params params = {dc_state->streams, dc_state->stream_count};
> +	bool set_backlight_level = false;
>   
>   	/* Disable writeback */
>   	for_each_old_connector_in_state(state, connector, old_con_state, i) {
> @@ -9530,6 +9531,7 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
>   			acrtc->hw_mode = new_crtc_state->mode;
>   			crtc->hwmode = new_crtc_state->mode;
>   			mode_set_reset_required = true;
> +			set_backlight_level = true;
>   		} else if (modereset_required(new_crtc_state)) {
>   			drm_dbg_atomic(dev,
>   				       "Atomic commit: RESET. crtc id %d:[%p]\n",
> @@ -9581,6 +9583,19 @@ static void amdgpu_dm_commit_streams(struct drm_atomic_state *state,
>   				acrtc->otg_inst = status->primary_otg_inst;
>   		}
>   	}
> +
> +	/* During boot up and resume the DC layer will reset the panel brightness
> +	 * to fix a flicker issue.
> +	 * It will cause the dm->actual_brightness is not the current panel brightness
> +	 * level. (the dm->brightness is the correct panel level)
> +	 * So we set the backlight level with dm->brightness value after set mode
> +	 */
> +	if (set_backlight_level) {
> +		for (i = 0; i < dm->num_of_edps; i++) {
> +			if (dm->backlight_dev[i])
> +				amdgpu_dm_backlight_set_level(dm, i, dm->brightness[i]);
> +		}
> +	}
>   }
>   
>   static void dm_set_writeback(struct amdgpu_display_manager *dm,