drm/radeon: track whether the GPU controls the backlight (v2)

A table in the vbios tells us whether the GPU backlight controller
is used or not.  If the bit is set, the GPU backlight controller is
used; if it is not set, an off-chip backlight controller is used.

v2: store all the firmware flags, not just BL control
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -1254,6 +1254,10 @@ bool radeon_atom_get_clock_info(struct drm_device *dev)
 		if (rdev->clock.max_pixel_clock == 0)
 			rdev->clock.max_pixel_clock = 40000;
 
+		/* not technically a clock, but... */
+		rdev->mode_info.firmware_flags =
+			le16_to_cpu(firmware_info->info.usFirmwareCapability.susAccess);
+
 		return true;
 	}
 

drivers/gpu/drm/radeon/radeon_mode.h

@@ -252,6 +252,8 @@ struct radeon_mode_info {
 
 	/* pointer to fbdev info structure */
 	struct radeon_fbdev *rfbdev;
+	/* firmware flags */
+	u16 firmware_flags;
 };
 
 #define MAX_H_CODE_TIMING_LEN 32