drm/msm/dsi: Parse DSI lanes via DT

The DSI driver is currently unaware of how the DSI physical data lanes
are mapped to the logical lanes provided by the DSI controller.

Create a DT binding "qcom,data-lane-map" that provides this information
on a given platform.

The MSM DSI controller is restricted in terms of what all mappings
it can support. The lane polarity is fixed for all the lanes, the clock
lanes are fixed, and the data lanes can be swapped among each other only
for a few combinations. Apply these restrictions when we parse the DT
data.

Cc: devicetree@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>

1 files changed, 29 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/display/msm/dsi.txt b/Documentation/devicetree/bindings/display/msm/dsi.txt
index e7423bea1424..f5948c48b9a2 100644
--- a/Documentation/devicetree/bindings/display/msm/dsi.txt
+++ b/Documentation/devicetree/bindings/display/msm/dsi.txt
@@ -44,9 +44,34 @@ Optional properties:
 - pinctrl-names: the pin control state names; should contain "default"
 - pinctrl-0: the default pinctrl state (active)
 - pinctrl-n: the "sleep" pinctrl state
-- port: DSI controller output port. This contains one endpoint subnode, with its
-  remote-endpoint set to the phandle of the connected panel's endpoint.
-  See Documentation/devicetree/bindings/graph.txt for device graph info.
+- port: DSI controller output port, containing one endpoint subnode.
+
+  DSI Endpoint properties:
+  - remote-endpoint: set to phandle of the connected panel's endpoint.
+    See Documentation/devicetree/bindings/graph.txt for device graph info.
+  - qcom,data-lane-map: this describes how the logical DSI lanes are mapped
+    to the physical lanes on the given platform. The value contained in
+    index n describes what logical data lane is mapped to the physical data
+    lane n (DATAn, where n lies between 0 and 3).
+
+    For example:
+
+    qcom,data-lane-map = <3 0 1 2>;
+
+    The above mapping describes that the logical data lane DATA3 is mapped to
+    the physical data lane DATA0, logical DATA0 to physical DATA1, logic DATA1
+    to phys DATA2 and logic DATA2 to phys DATA3.
+
+    There are only a limited number of physical to logical mappings possible:
+
+    "0123": Logic 0->Phys 0; Logic 1->Phys 1; Logic 2->Phys 2; Logic 3->Phys 3;
+    "3012": Logic 3->Phys 0; Logic 0->Phys 1; Logic 1->Phys 2; Logic 2->Phys 3;
+    "2301": Logic 2->Phys 0; Logic 3->Phys 1; Logic 0->Phys 2; Logic 1->Phys 3;
+    "1230": Logic 1->Phys 0; Logic 2->Phys 1; Logic 3->Phys 2; Logic 0->Phys 3;
+    "0321": Logic 0->Phys 0; Logic 3->Phys 1; Logic 2->Phys 2; Logic 1->Phys 3;
+    "1032": Logic 1->Phys 0; Logic 0->Phys 1; Logic 3->Phys 2; Logic 2->Phys 3;
+    "2103": Logic 2->Phys 0; Logic 1->Phys 1; Logic 0->Phys 2; Logic 3->Phys 3;
+    "3210": Logic 3->Phys 0; Logic 2->Phys 1; Logic 1->Phys 2; Logic 0->Phys 3;
 
 DSI PHY:
 Required properties:
@@ -131,6 +156,7 @@ Example:
 		port {
 			dsi0_out: endpoint {
 				remote-endpoint = <&panel_in>;
+				lanes = <0 1 2 3>;
 			};
 		};
 	};