drm/amd/display: Added support for multiple eDP BL control

[WHY & HOW]
Driver currently assumes only 1 eDP is connected. Added support for
multiple eDP BL control.
Signed-off-by: Jake Wang <haonan.wang2@amd.com>
Acked-by: Bindu Ramamurthy <bindur12@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_hwseq.c

@@ -218,6 +218,8 @@ bool dcn21_set_backlight_level(struct pipe_ctx *pipe_ctx,
 	cmd.abm_set_backlight.header.sub_type = DMUB_CMD__ABM_SET_BACKLIGHT;
 	cmd.abm_set_backlight.abm_set_backlight_data.frame_ramp = frame_ramp;
 	cmd.abm_set_backlight.abm_set_backlight_data.backlight_user_level = backlight_pwm_u16_16;
+	cmd.abm_set_backlight.abm_set_backlight_data.version = DMUB_CMD_ABM_SET_BACKLIGHT_VERSION_1;
+	cmd.abm_set_backlight.abm_set_backlight_data.panel_mask = (0x01 << panel_cntl->inst);
 	cmd.abm_set_backlight.header.payload_bytes = sizeof(struct dmub_cmd_abm_set_backlight_data);
 
 	dc_dmub_srv_cmd_queue(dc->dmub_srv, &cmd);

drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h

@@ -120,6 +120,16 @@
 /* Trace buffer offset for entry */
 #define TRACE_BUFFER_ENTRY_OFFSET  16
 
+/**
+ * ABM backlight control version legacy
+ */
+#define DMUB_CMD_ABM_SET_BACKLIGHT_VERSION_UNKNOWN 0x0
+
+/**
+ * ABM backlight control version with multi edp support
+ */
+#define DMUB_CMD_ABM_SET_BACKLIGHT_VERSION_1 0x1
+
 /**
  * Physical framebuffer address location, 64-bit.
  */
@@ -1625,6 +1635,23 @@ struct dmub_cmd_abm_set_backlight_data {
 	 * Requested backlight level from user.
 	 */
 	uint32_t backlight_user_level;
+
+	/**
+	 * Backlight data version.
+	 */
+	uint8_t version;
+
+	/**
+	 * Panel Control HW instance mask.
+	 * Bit 0 is Panel Control HW instance 0.
+	 * Bit 1 is Panel Control HW instance 1.
+	 */
+	uint8_t panel_mask;
+
+	/**
+	 * Explicit padding to 4 byte boundary.
+	 */
+	uint8_t pad[2];
 };
 
 /**