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, 96 insertions, 20 deletions

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 69bac59ceca1..4282ec6bbaaf 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -163,6 +163,10 @@ struct msm_dsi_host {
 	enum mipi_dsi_pixel_format format;
 	unsigned long mode_flags;
 
+	/* lane data parsed via DT */
+	int dlane_swap;
+	int num_data_lanes;
+
 	u32 dma_cmd_ctrl_restore;
 
 	bool registered;
@@ -845,19 +849,10 @@ 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,
@@ -1479,6 +1474,9 @@ 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 > msm_host->num_data_lanes)
+		return -EINVAL;
+
 	msm_host->channel = dsi->channel;
 	msm_host->lanes = dsi->lanes;
 	msm_host->format = dsi->format;
@@ -1532,6 +1530,75 @@ static struct mipi_dsi_host_ops dsi_host_ops = {
 	.transfer = dsi_host_transfer,
 };
 
+/*
+ * List of supported physical to logical lane mappings.
+ * For example, the 2nd entry represents the following mapping:
+ *
+ * "3012": Logic 3->Phys 0; Logic 0->Phys 1; Logic 1->Phys 2; Logic 2->Phys 3;
+ */
+static const int supported_data_lane_swaps[][4] = {
+	{ 0, 1, 2, 3 },
+	{ 3, 0, 1, 2 },
+	{ 2, 3, 0, 1 },
+	{ 1, 2, 3, 0 },
+	{ 0, 3, 2, 1 },
+	{ 1, 0, 3, 2 },
+	{ 2, 1, 0, 3 },
+	{ 3, 2, 1, 0 },
+};
+
+static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host,
+				    struct device_node *ep)
+{
+	struct device *dev = &msm_host->pdev->dev;
+	struct property *prop;
+	u32 lane_map[4];
+	int ret, i, len, num_lanes;
+
+	prop = of_find_property(ep, "qcom,data-lane-map", &len);
+	if (!prop) {
+		dev_dbg(dev, "failed to find data lane mapping\n");
+		return -EINVAL;
+	}
+
+	num_lanes = len / sizeof(u32);
+
+	if (num_lanes < 1 || num_lanes > 4) {
+		dev_err(dev, "bad number of data lanes\n");
+		return -EINVAL;
+	}
+
+	msm_host->num_data_lanes = num_lanes;
+
+	ret = of_property_read_u32_array(ep, "qcom,data-lane-map", lane_map,
+					 num_lanes);
+	if (ret) {
+		dev_err(dev, "failed to read lane data\n");
+		return ret;
+	}
+
+	/*
+	 * compare DT specified physical-logical lane mappings with the ones
+	 * supported by hardware
+	 */
+	for (i = 0; i < ARRAY_SIZE(supported_data_lane_swaps); i++) {
+		const int *swap = supported_data_lane_swaps[i];
+		int j;
+
+		for (j = 0; j < num_lanes; j++) {
+			if (swap[j] != lane_map[j])
+				break;
+		}
+
+		if (j == num_lanes) {
+			msm_host->dlane_swap = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
 static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)
 {
 	struct device *dev = &msm_host->pdev->dev;
@@ -1558,17 +1625,21 @@ static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)
 		return 0;
 	}
 
+	ret = dsi_host_parse_lane_data(msm_host, endpoint);
+	if (ret) {
+		dev_err(dev, "%s: invalid lane configuration %d\n",
+			__func__, ret);
+		goto err;
+	}
+
 	/* Get panel node from the output port's endpoint data */
 	device_node = of_graph_get_remote_port_parent(endpoint);
 	if (!device_node) {
 		dev_err(dev, "%s: no valid device\n", __func__);
-		of_node_put(endpoint);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto err;
 	}
 
-	of_node_put(endpoint);
-	of_node_put(device_node);
-
 	msm_host->device_node = device_node;
 
 	if (of_property_read_bool(np, "syscon-sfpb")) {
@@ -1577,11 +1648,16 @@ static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)
 		if (IS_ERR(msm_host->sfpb)) {
 			dev_err(dev, "%s: failed to get sfpb regmap\n",
 				__func__);
-			return PTR_ERR(msm_host->sfpb);
+			ret = PTR_ERR(msm_host->sfpb);
 		}
 	}
 
-	return 0;
+	of_node_put(device_node);
+
+err:
+	of_node_put(endpoint);
+
+	return ret;
 }
 
 int msm_dsi_host_init(struct msm_dsi *msm_dsi)