drm/radeon/kms/atom: force bpc to 8 for now

Using the bpc (bits per color) specified by the monitor
can cause problems in some cases.  Until we get a better
handle on how to deal with those cases, just use a bpc of 8.
Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -588,8 +588,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
 		if (encoder->crtc == crtc) {
 			radeon_encoder = to_radeon_encoder(encoder);
 			connector = radeon_get_connector_for_encoder(encoder);
-			if (connector && connector->display_info.bpc)
-				bpc = connector->display_info.bpc;
+			/* if (connector && connector->display_info.bpc)
+				bpc = connector->display_info.bpc; */
 			encoder_mode = atombios_get_encoder_mode(encoder);
 			is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
 			if ((radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT | ATOM_DEVICE_DFP_SUPPORT)) ||
@@ -965,7 +965,9 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
 		struct radeon_connector_atom_dig *dig_connector =
 			radeon_connector->con_priv;
 		int dp_clock;
-		bpc = connector->display_info.bpc;
+
+		/* if (connector->display_info.bpc)
+			bpc = connector->display_info.bpc; */
 
 		switch (encoder_mode) {
 		case ATOM_ENCODER_MODE_DP_MST:

drivers/gpu/drm/radeon/atombios_dp.c

@@ -405,10 +405,13 @@ static void dp_get_adjust_train(u8 link_status[DP_LINK_STATUS_SIZE],
 /* get bpc from the EDID */
 static int convert_bpc_to_bpp(int bpc)
 {
+#if 0
 	if (bpc == 0)
 		return 24;
 	else
 		return bpc * 3;
+#endif
+	return 24;
 }
 
 /* get the max pix clock supported by the link rate and lane num */

drivers/gpu/drm/radeon/atombios_encoders.c

@@ -541,7 +541,7 @@ atombios_dig_encoder_setup(struct drm_encoder *encoder, int action, int panel_mo
 		dp_clock = dig_connector->dp_clock;
 		dp_lane_count = dig_connector->dp_lane_count;
 		hpd_id = radeon_connector->hpd.hpd;
-		bpc = connector->display_info.bpc;
+		/* bpc = connector->display_info.bpc; */
 	}
 
 	/* no dig encoder assigned */
@@ -1159,7 +1159,7 @@ atombios_external_encoder_setup(struct drm_encoder *encoder,
 		dp_lane_count = dig_connector->dp_lane_count;
 		connector_object_id =
 			(radeon_connector->connector_object_id & OBJECT_ID_MASK) >> OBJECT_ID_SHIFT;
-		bpc = connector->display_info.bpc;
+		/* bpc = connector->display_info.bpc; */
 	}
 
 	memset(&args, 0, sizeof(args));