drm/i915: wait for all DSI FIFOs to be empty

Ensure that the DSI packets for a particular sequence are completely
sent before going ahead in the enabling or disabling of the panel
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dsi.c

@@ -152,6 +152,8 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
 		if (intel_dsi->dev.dev_ops->enable)
 			intel_dsi->dev.dev_ops->enable(&intel_dsi->dev);
 
+		wait_for_dsi_fifo_empty(intel_dsi);
+
 		/* assert ip_tg_enable signal */
 		temp = I915_READ(MIPI_PORT_CTRL(pipe)) & ~LANE_CONFIGURATION_MASK;
 		temp = temp | intel_dsi->port_bits;
@@ -192,6 +194,8 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder)
 	if (intel_dsi->dev.dev_ops->send_otp_cmds)
 		intel_dsi->dev.dev_ops->send_otp_cmds(&intel_dsi->dev);
 
+	wait_for_dsi_fifo_empty(intel_dsi);
+
 	/* Enable port in pre-enable phase itself because as per hw team
 	 * recommendation, port should be enabled befor plane & pipe */
 	intel_dsi_enable(encoder);
@@ -232,6 +236,8 @@ static void intel_dsi_disable(struct intel_encoder *encoder)
 	DRM_DEBUG_KMS("\n");
 
 	if (is_vid_mode(intel_dsi)) {
+		wait_for_dsi_fifo_empty(intel_dsi);
+
 		/* de-assert ip_tg_enable signal */
 		temp = I915_READ(MIPI_PORT_CTRL(pipe));
 		I915_WRITE(MIPI_PORT_CTRL(pipe), temp & ~DPI_ENABLE);
@@ -261,6 +267,8 @@ static void intel_dsi_disable(struct intel_encoder *encoder)
 	 * some next enable sequence send turn on packet error is observed */
 	if (intel_dsi->dev.dev_ops->disable)
 		intel_dsi->dev.dev_ops->disable(&intel_dsi->dev);
+
+	wait_for_dsi_fifo_empty(intel_dsi);
 }
 
 static void intel_dsi_clear_device_ready(struct intel_encoder *encoder)

drivers/gpu/drm/i915/intel_dsi_cmd.c

@@ -419,3 +419,19 @@ int dpi_send_cmd(struct intel_dsi *intel_dsi, u32 cmd, bool hs)
 
 	return 0;
 }
+
+void wait_for_dsi_fifo_empty(struct intel_dsi *intel_dsi)
+{
+	struct drm_encoder *encoder = &intel_dsi->base.base;
+	struct drm_device *dev = encoder->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->crtc);
+	enum pipe pipe = intel_crtc->pipe;
+	u32 mask;
+
+	mask = LP_CTRL_FIFO_EMPTY | HS_CTRL_FIFO_EMPTY |
+					LP_DATA_FIFO_EMPTY | HS_DATA_FIFO_EMPTY;
+
+	if (wait_for((I915_READ(MIPI_GEN_FIFO_STAT(pipe)) & mask) == mask, 100))
+		DRM_ERROR("DPI FIFOs are not empty\n");
+}

drivers/gpu/drm/i915/intel_dsi_cmd.h

@@ -51,6 +51,7 @@ int dsi_vc_generic_read(struct intel_dsi *intel_dsi, int channel,
 			u8 *reqdata, int reqlen, u8 *buf, int buflen);
 
 int dpi_send_cmd(struct intel_dsi *intel_dsi, u32 cmd, bool hs);
+void wait_for_dsi_fifo_empty(struct intel_dsi *intel_dsi);
 
 /* XXX: questionable write helpers */
 static inline int dsi_vc_dcs_write_0(struct intel_dsi *intel_dsi,