drm/amd/display: Detach backlight from stream

[Why]
Backlight is conceptually a property of links, not streams.
All backlight programming is done on links, but there is a
stream property bl_pwm_level that is used to restore backlight
on dpms on and s3 resume.  This is unnecessary, as backlight
is already restored by hardware with no driver intervention.

[How]
Remove bl_pwm_level, and the stream argument to set_backlight
Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1760,7 +1760,7 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
 		+ caps.min_input_signal * 0x101;
 
 	if (dc_link_set_backlight_level(dm->backlight_link,
-			brightness, 0, 0))
+			brightness, 0))
 		return 0;
 	else
 		return 1;

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -2186,8 +2186,7 @@ int dc_link_get_backlight_level(const struct dc_link *link)
 
 bool dc_link_set_backlight_level(const struct dc_link *link,
 		uint32_t backlight_pwm_u16_16,
-		uint32_t frame_ramp,
-		const struct dc_stream_state *stream)
+		uint32_t frame_ramp)
 {
 	struct dc  *core_dc = link->ctx->dc;
 	struct abm *abm = core_dc->res_pool->abm;
@@ -2202,10 +2201,6 @@ bool dc_link_set_backlight_level(const struct dc_link *link,
 		(abm->funcs->set_backlight_level_pwm == NULL))
 		return false;
 
-	if (stream)
-		((struct dc_stream_state *)stream)->bl_pwm_level =
-				backlight_pwm_u16_16;
-
 	use_smooth_brightness = dmcu->funcs->is_dmcu_initialized(dmcu);
 
 	DC_LOG_BACKLIGHT("New Backlight level: %d (0x%X)\n",
@@ -2633,11 +2628,6 @@ void core_link_enable_stream(
 
 		if (dc_is_dp_signal(pipe_ctx->stream->signal))
 			enable_stream_features(pipe_ctx);
-
-		dc_link_set_backlight_level(pipe_ctx->stream->link,
-				pipe_ctx->stream->bl_pwm_level,
-				0,
-				pipe_ctx->stream);
 	}
 
 }

drivers/gpu/drm/amd/display/dc/dc_link.h

@@ -147,8 +147,7 @@ static inline struct dc_link *dc_get_link_at_index(struct dc *dc, uint32_t link_
  */
 bool dc_link_set_backlight_level(const struct dc_link *dc_link,
 		uint32_t backlight_pwm_u16_16,
-		uint32_t frame_ramp,
-		const struct dc_stream_state *stream);
+		uint32_t frame_ramp);
 
 int dc_link_get_backlight_level(const struct dc_link *dc_link);
 

drivers/gpu/drm/amd/display/dc/dc_stream.h

@@ -100,7 +100,6 @@ struct dc_stream_state {
 
 	/* DMCU info */
 	unsigned int abm_level;
-	unsigned int bl_pwm_level;
 
 	/* from core_stream struct */
 	struct dc_context *ctx;