[Intel-gfx] [RFC 06/14] drm/i915: Disable vlank interrupt for disabling MIPI cmd mode

[Gaurav K Singh]

vblank interrupt should be disabled before starting the disable
sequence for MIPI command mode. Otherwise when pipe is disabled
TE interurpt will be still handled and one memory write command
will be sent with pipe disabled. This makes the pipe hw to get
stuck and it doesn't recover in the next enable sequence causing
display blank out.

v2: Use drm_blank_off instead of platform specific disable vblank functions (Daniel)

Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu at intel.com>
Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>
---
 drivers/gpu/drm/i915/intel_dsi.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index d378246..7021591 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -513,11 +513,25 @@ static void intel_dsi_enable_nop(struct intel_encoder *encoder)
 
 static void intel_dsi_pre_disable(struct intel_encoder *encoder)
 {
+	struct drm_device *dev = encoder->base.dev;
 	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
+	int pipe = intel_crtc->pipe;
 	enum port port;
 
 	DRM_DEBUG_KMS("\n");
 
+	if (is_cmd_mode(intel_dsi)) {
+		drm_vblank_off(dev, pipe);
+
+		/*
+		 * Make sure that the last frame is sent otherwise pipe can get
+		 * stuck. Currently providing delay time for ~2 vblanks
+		 * assuming 60fps.
+		 */
+		mdelay(40);
+	}
+
 	if (is_vid_mode(intel_dsi)) {
 		/* Send Shutdown command to the panel in LP mode */
 		for_each_dsi_port(port, intel_dsi->ports)
-- 
1.7.9.5