Re: [PATCH] drm/msm/dsi: Parse lane swap information from DT

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Hi,

On 9/4/2015 12:00 AM, Hai Li wrote:
Lane swap configuration is based on the board design.
This change allows the DSI host to get this information
from device tree, instead of hardcoding in driver.

Signed-off-by: Hai Li <hali@xxxxxxxxxxxxxx>
---
  Documentation/devicetree/bindings/drm/msm/dsi.txt | 13 ++++++
  drivers/gpu/drm/msm/dsi/dsi_host.c                | 49 +++++++++++++++++------
  2 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/Documentation/devicetree/bindings/drm/msm/dsi.txt b/Documentation/devicetree/bindings/drm/msm/dsi.txt
index d56923c..febcc51 100644
--- a/Documentation/devicetree/bindings/drm/msm/dsi.txt
+++ b/Documentation/devicetree/bindings/drm/msm/dsi.txt
@@ -44,6 +44,17 @@ Optional properties:
  - 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.
+- qcom,dsi-logical-lane-swap: Character string to swap logical lane to physical
+  lane mapping. Supported lane mappings:
+  "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;
+  Default value is "0123", which means no lane swap.

  DSI PHY:
  Required properties:
@@ -129,6 +140,8 @@ Example:
  				remote-endpoint = <&panel_in>;
  			};
  		};
+
+		qcom,dsi-logical-lane-swap = "0123";
  	};

I think we could keep this in the output port DT node instead,
since it is more of a property of how it connects to the panel.

There is a more generic way to represent lane info. It would be nice to
have a look at what's done here:

http://marc.info/?l=linux-omap&m=133605367610068&w=2

and it's usage here:

http://lxr.free-electrons.com/source/arch/arm/boot/dts/omap4-sdp.dts#L647

Thanks,
Archit



  	mdss_dsi_phy0: qcom,mdss_dsi_phy@fd922a00 {
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 8d82973f..eaba417 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -131,6 +131,7 @@ struct msm_dsi_host {
  	enum mipi_dsi_pixel_format format;
  	unsigned long mode_flags;

+	u32 dlane_swap;
  	u32 dma_cmd_ctrl_restore;

  	bool registered;
@@ -684,19 +685,9 @@ static void dsi_ctrl_config(struct msm_dsi_host *msm_host, bool enable,
  	data = DSI_CTRL_CLK_EN;

  	DBG("lane number=%d", msm_host->lanes);
-	if (msm_host->lanes == 2) {
-		data |= DSI_CTRL_LANE1 | DSI_CTRL_LANE2;
-		/* swap lanes for 2-lane panel for better performance */
-		dsi_write(msm_host, REG_DSI_LANE_SWAP_CTRL,
-			DSI_LANE_SWAP_CTRL_DLN_SWAP_SEL(LANE_SWAP_1230));
-	} else {
-		/* Take 4 lanes as default */
-		data |= DSI_CTRL_LANE0 | DSI_CTRL_LANE1 | DSI_CTRL_LANE2 |
-			DSI_CTRL_LANE3;
-		/* Do not swap lanes for 4-lane panel */
-		dsi_write(msm_host, REG_DSI_LANE_SWAP_CTRL,
-			DSI_LANE_SWAP_CTRL_DLN_SWAP_SEL(LANE_SWAP_0123));
-	}
+	data |= ((DSI_CTRL_LANE0 << msm_host->lanes) - DSI_CTRL_LANE0);
+	dsi_write(msm_host, REG_DSI_LANE_SWAP_CTRL,
+		DSI_LANE_SWAP_CTRL_DLN_SWAP_SEL(msm_host->dlane_swap));

  	if (!(flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
  		dsi_write(msm_host, REG_DSI_LANE_CTRL,
@@ -1289,6 +1280,9 @@ static int dsi_host_attach(struct mipi_dsi_host *host,
  	struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
  	int ret;

+	if (dsi->lanes > 4 || dsi->channel > 3)
+		return -EINVAL;
+
  	msm_host->channel = dsi->channel;
  	msm_host->lanes = dsi->lanes;
  	msm_host->format = dsi->format;
@@ -1344,6 +1338,33 @@ static struct mipi_dsi_host_ops dsi_host_ops = {
  	.transfer = dsi_host_transfer,
  };

+static void dsi_parse_dlane_swap(struct msm_dsi_host *msm_host,
+				struct device_node *np)
+{
+	const char *lane_swap;
+
+	lane_swap = of_get_property(np, "qcom,dsi-logical-lane-swap", NULL);
+
+	if (!lane_swap)
+		msm_host->dlane_swap = LANE_SWAP_0123;
+	else if (!strncmp(lane_swap, "3012", 5))
+		msm_host->dlane_swap = LANE_SWAP_3012;
+	else if (!strncmp(lane_swap, "2301", 5))
+		msm_host->dlane_swap = LANE_SWAP_2301;
+	else if (!strncmp(lane_swap, "1230", 5))
+		msm_host->dlane_swap = LANE_SWAP_1230;
+	else if (!strncmp(lane_swap, "0321", 5))
+		msm_host->dlane_swap = LANE_SWAP_0321;
+	else if (!strncmp(lane_swap, "1032", 5))
+		msm_host->dlane_swap = LANE_SWAP_1032;
+	else if (!strncmp(lane_swap, "2103", 5))
+		msm_host->dlane_swap = LANE_SWAP_2103;
+	else if (!strncmp(lane_swap, "3210", 5))
+		msm_host->dlane_swap = LANE_SWAP_3210;
+	else
+		msm_host->dlane_swap = LANE_SWAP_0123;
+}
+
  static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)
  {
  	struct device *dev = &msm_host->pdev->dev;
@@ -1358,6 +1379,8 @@ static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)
  		return ret;
  	}

+	dsi_parse_dlane_swap(msm_host, np);
+
  	/*
  	 * Get the first endpoint node. In our case, dsi has one output port
  	 * to which the panel is connected. Don't return an error if a port


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