fix Hsync and Vsync polarity can't change from negatieve to positief … (#6193)

vc4/hdmi: Fix Hsync and Vsync polarity changes

Polarity bits were only ever set and never cleared.
Make sure they can also be cleared.

Signed-off-by: Michiel Vanbiervliet <[email protected]>

Author: Michiiel

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -1893,14 +1893,15 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
 
 	HDMI_WRITE(HDMI_VID_CTL,
-		   HDMI_READ(HDMI_VID_CTL) |
-		   VC4_HD_VID_CTL_ENABLE |
-		   VC4_HD_VID_CTL_CLRRGB |
-		   VC4_HD_VID_CTL_UNDERFLOW_ENABLE |
-		   VC4_HD_VID_CTL_FRAME_COUNTER_RESET |
-		   VC4_HD_VID_CTL_BLANK_INSERT_EN |
-		   (vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
-		   (hsync_pos ? 0 : VC4_HD_VID_CTL_HSYNC_LOW));
+	   (HDMI_READ(HDMI_VID_CTL) &~ 
+	   (VC4_HD_VID_CTL_VSYNC_LOW | VC4_HD_VID_CTL_HSYNC_LOW)) |
+	   VC4_HD_VID_CTL_ENABLE |
+	   VC4_HD_VID_CTL_CLRRGB |
+	   VC4_HD_VID_CTL_UNDERFLOW_ENABLE |
+	   VC4_HD_VID_CTL_FRAME_COUNTER_RESET |
+	   VC4_HD_VID_CTL_BLANK_INSERT_EN |
+	   (vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
+	   (hsync_pos ? 0 : VC4_HD_VID_CTL_HSYNC_LOW));
 
 	HDMI_WRITE(HDMI_VID_CTL,
 		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_BLANKPIX);