drm/amd/display: Add VC for VESA Aux Backlight Control

[WHY]
There is no way to distinguish
the static backlight control type
being used and the VABC support
without the use of a debugger or
reading DPCD registers.

[HOW]
Add Visual Confirm support
for VESA Aux-based Backlight Control.

Reviewed-by: Harry Vanzylldejong <[e-mail]>
Signed-off-by: Iswara Nagulendran <[e-mail]>
Signed-off-by: Roman Li <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 				get_mclk_switch_visual_confirm_color(pipe_ctx, &(pipe_ctx->visual_confirm_color));
 			else if (dc->debug.visual_confirm == VISUAL_CONFIRM_FAMS2)
 				get_fams2_visual_confirm_color(dc, context, pipe_ctx, &(pipe_ctx->visual_confirm_color));
+			else if (dc->debug.visual_confirm == VISUAL_CONFIRM_VABC)
+				get_vabc_visual_confirm_color(pipe_ctx, &(pipe_ctx->visual_confirm_color));
 		}
 	}
 }

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

···
 	}
 }
 
+/* Visual Confirm color definition for VABC */
+void get_vabc_visual_confirm_color(
+	struct pipe_ctx *pipe_ctx,
+	struct tg_color *color)
+{
+	uint32_t color_value = MAX_TG_COLOR_VALUE;
+	struct dc_link *edp_link = NULL;
+
+	if (pipe_ctx && pipe_ctx->stream && pipe_ctx->stream->link) {
+		if (pipe_ctx->stream->link->connector_signal == SIGNAL_TYPE_EDP)
+			edp_link = pipe_ctx->stream->link;
+	}
+
+	if (edp_link) {
+		switch (edp_link->backlight_control_type) {
+		case BACKLIGHT_CONTROL_PWM:
+			color->color_r_cr = color_value;
+			color->color_g_y = 0;
+			color->color_b_cb = 0;
+			break;
+		case BACKLIGHT_CONTROL_AMD_AUX:
+			color->color_r_cr = 0;
+			color->color_g_y = color_value;
+			color->color_b_cb = 0;
+			break;
+		case BACKLIGHT_CONTROL_VESA_AUX:
+			color->color_r_cr = 0;
+			color->color_g_y = 0;
+			color->color_b_cb = color_value;
+			break;
+		}
+	} else {
+		color->color_r_cr = 0;
+		color->color_g_y = 0;
+		color->color_b_cb = 0;
+	}
+}
+
 void get_subvp_visual_confirm_color(
 		struct pipe_ctx *pipe_ctx,
 		struct tg_color *color)

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

···
 	VISUAL_CONFIRM_MCLK_SWITCH = 16,
 	VISUAL_CONFIRM_FAMS2 = 19,
 	VISUAL_CONFIRM_HW_CURSOR = 20,
+	VISUAL_CONFIRM_VABC = 21,
 };
 
 enum dc_psr_power_opts {

drivers/gpu/drm/amd/display/dc/hwss/hw_sequencer.h

···
 	DMUB_SUBVP_SAVE_SURF_ADDR,
 	HUBP_WAIT_FOR_DCC_META_PROP,
 	DMUB_FAMS2_GLOBAL_CONTROL_LOCK_FAST,
-
 };
 
 struct block_sequence {
···
 void get_mpctree_visual_confirm_color(
 		struct pipe_ctx *pipe_ctx,
 		struct tg_color *color);
-
+void get_vabc_visual_confirm_color(
+	struct pipe_ctx *pipe_ctx,
+	struct tg_color *color);
 void get_subvp_visual_confirm_color(
 	struct pipe_ctx *pipe_ctx,
 	struct tg_color *color);
-
 void get_fams2_visual_confirm_color(
 	struct dc *dc,
 	struct dc_state *context,