[Intel-gfx] [PATCH] drm/i915: Add DPI FIFO empty status check

[Deepak M]

From: Gaurav K Singh <gaurav.k.singh at intel.com>

Before sending TURN ON packet,check the DPI
FIFO empty status.

v2: Change in commit message
    Checking for FIFO empty  only during TURN ON packet.

Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>
Signed-off-by: Deepak M <m.deepak at intel.com>
---
Got to know about the patch where they are removing this
DPI FIFO empty check while sending the SHUTDOWN packet.

http://lists.freedesktop.org/archives/intel-gfx/2014-July/048401.html

According added the check and waiting for DPI FIFIO empty
only when TURN_ON packet is sent.

 drivers/gpu/drm/i915/intel_dsi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index 170ae6f..495056f 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -222,6 +222,12 @@ static int dpi_send_cmd(struct intel_dsi *intel_dsi, u32 cmd, bool hs,
 	else
 		cmd |= DPI_LP_MODE;
 
+	mask = DPI_FIFO_EMPTY;
+
+	if ((cmd & TURN_ON) && wait_for((I915_READ(MIPI_GEN_FIFO_STAT(port)) &
+			mask) == mask, 50))
+		DRM_ERROR("Timeout waiting for DPI FIFO empty\n");
+
 	/* clear bit */
 	I915_WRITE(MIPI_INTR_STAT(port), SPL_PKT_SENT_INTERRUPT);
 
-- 
1.9.1