[PATCH 4.9 90/92] drm: rcar-du: Use the VBK interrupt for vblank events

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>

commit cbbb90b0c084d7dfb2ed8e3fecf8df200fbdd2a0 upstream.

When implementing support for interlaced modes, the driver switched from
reporting vblank events on the vertical blanking (VBK) interrupt to the
frame end interrupt (FRM). This incorrectly divided the reported refresh
rate by two. Fix it by moving back to the VBK interrupt.

Fixes: 906eff7fcada ("drm: rcar-du: Implement support for interlaced modes")
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
Signed-off-by: thongsyho <thong.ho.px@xxxxxxxxxxxxxxx>
Signed-off-by: Nhan Nguyen <nhan.nguyen.yb@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/rcar-du/rcar_du_crtc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -551,7 +551,7 @@ static irqreturn_t rcar_du_crtc_irq(int
 	status = rcar_du_crtc_read(rcrtc, DSSR);
 	rcar_du_crtc_write(rcrtc, DSRCR, status & DSRCR_MASK);
 
-	if (status & DSSR_FRM) {
+	if (status & DSSR_VBK) {
 		drm_crtc_handle_vblank(&rcrtc->crtc);
 		rcar_du_crtc_finish_page_flip(rcrtc);
 		ret = IRQ_HANDLED;