dt-bindings: msm/dsi: Add mdp transfer time to msm dsi binding

Adds mdp transfer time to msm dsi binding

Changes in v3:
- Added Rob's R-b
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Rajesh Yadav <ryadav@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

Documentation/devicetree/bindings/display/msm/dsi.txt

@@ -121,6 +121,20 @@ Required properties:
 Optional properties:
 - qcom,dsi-phy-regulator-ldo-mode: Boolean value indicating if the LDO mode PHY
   regulator is wanted.
+- qcom,mdss-mdp-transfer-time-us:	Specifies the dsi transfer time for command mode
+					panels in microseconds. Driver uses this number to adjust
+					the clock rate according to the expected transfer time.
+					Increasing this value would slow down the mdp processing
+					and can result in slower performance.
+					Decreasing this value can speed up the mdp processing,
+					but this can also impact power consumption.
+					As a rule this time should not be higher than the time
+					that would be expected with the processing at the
+					dsi link rate since anyways this would be the maximum
+					transfer time that could be achieved.
+					If ping pong split is enabled, this time should not be higher
+					than two times the dsi link rate time.
+					If the property is not specified, then the default value is 14000 us.
 
 [1] Documentation/devicetree/bindings/clock/clock-bindings.txt
 [2] Documentation/devicetree/bindings/graph.txt
@@ -171,6 +185,8 @@ Example:
 		qcom,master-dsi;
 		qcom,sync-dual-dsi;
 
+		qcom,mdss-mdp-transfer-time-us = <12000>;
+
 		pinctrl-names = "default", "sleep";
 		pinctrl-0 = <&dsi_active>;
 		pinctrl-1 = <&dsi_suspend>;