Merge "msm: mdss: Allow WB to use first available control path"

1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/video/fbdev/msm/mdss_mdp.h b/drivers/video/fbdev/msm/mdss_mdp.h
index ab2a7184aa45..3bb936638a12 100644
--- a/drivers/video/fbdev/msm/mdss_mdp.h
+++ b/drivers/video/fbdev/msm/mdss_mdp.h
@@ -1322,12 +1322,21 @@ static inline int mdss_mdp_get_wb_ctl_support(struct mdss_data_type *mdata,
 							bool rotator_session)
 {
 	/*
-	 * Initial control paths are used for primary and external
-	 * interfaces and remaining control paths are used for WB
-	 * interfaces.
+	 * Any control path can be routed to any of the hardware datapaths.
+	 * But there is a HW restriction for 3D Mux block. As the 3D Mux
+	 * settings in the CTL registers are double buffered, if an interface
+	 * uses it and disconnects, then the subsequent interface which gets
+	 * connected should use the same control path in order to clear the
+	 * 3D MUX settings.
+	 * To handle this restriction, we are allowing WB also, to loop through
+	 * all the avialable control paths, so that it can reuse the control
+	 * path left by the external interface, thereby clearing the 3D Mux
+	 * settings.
+	 * The initial control paths can be used by Primary, External and WB.
+	 * The rotator can use the remaining available control paths.
 	 */
 	return rotator_session ? (mdata->nctl - mdata->nmixers_wb) :
-				(mdata->nctl - mdata->nwb);
+		MDSS_MDP_CTL0;
 }
 
 static inline bool mdss_mdp_is_nrt_vbif_client(struct mdss_data_type *mdata,