[PATCH v3 8/8] media: rcar-csi2: Negotiate data lanes number

[Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>]

Use the newly introduced get_mbus_config() subdevice pad operation to
retrieve the remote subdevice MIPI CSI-2 bus configuration and configure
the number of active data lanes accordingly.

In order to be able to call the remote subdevice operation cache the
index of the remote pad connected to the single CSI-2 input port.

Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
---
 drivers/media/platform/rcar-vin/rcar-csi2.c | 61 ++++++++++++++++++++-
 1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
index 151e6a90c5fb..11769f004fd8 100644
--- a/drivers/media/platform/rcar-vin/rcar-csi2.c
+++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
@@ -363,6 +363,7 @@ struct rcar_csi2 {
 	struct v4l2_async_notifier notifier;
 	struct v4l2_async_subdev asd;
 	struct v4l2_subdev *remote;
+	unsigned int remote_pad;
 
 	struct v4l2_mbus_framefmt mf;
 
@@ -371,6 +372,7 @@ struct rcar_csi2 {
 
 	unsigned short lanes;
 	unsigned char lane_swap[4];
+	unsigned short active_lanes;
 };
 
 static inline struct rcar_csi2 *sd_to_csi2(struct v4l2_subdev *sd)
@@ -414,7 +416,7 @@ static int rcsi2_wait_phy_start(struct rcar_csi2 *priv)
 
 	/* Wait for the clock and data lanes to enter LP-11 state. */
 	for (timeout = 0; timeout <= 20; timeout++) {
-		const u32 lane_mask = (1 << priv->lanes) - 1;
+		const u32 lane_mask = (1 << priv->active_lanes) - 1;
 
 		if ((rcsi2_read(priv, PHCLM_REG) & PHCLM_STOPSTATECKL)  &&
 		    (rcsi2_read(priv, PHDLM_REG) & lane_mask) == lane_mask)
@@ -471,11 +473,57 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp)
 	 * bps = link_freq * 2
 	 */
 	mbps = v4l2_ctrl_g_ctrl_int64(ctrl) * bpp;
-	do_div(mbps, priv->lanes * 1000000);
+	do_div(mbps, priv->active_lanes * 1000000);
 
 	return mbps;
 }
 
+static int rcsi2_config_active_lanes(struct rcar_csi2 *priv)
+{
+	struct v4l2_mbus_config mbus_config = { 0 };
+	unsigned int num_lanes = (-1U);
+	int ret;
+
+	priv->active_lanes = priv->lanes;
+	ret = v4l2_subdev_call(priv->remote, pad, get_mbus_config,
+			       priv->remote_pad, &mbus_config);
+	if (ret == -ENOIOCTLCMD) {
+		dev_dbg(priv->dev, "No remote mbus configuration available\n");
+		return 0;
+	}
+
+	if (ret) {
+		dev_err(priv->dev, "Failed to get remote mbus configuration\n");
+		return ret;
+	}
+
+	if (mbus_config.type != V4L2_MBUS_CSI2_DPHY) {
+		dev_err(priv->dev, "Unsupported media bus type %u\n",
+			mbus_config.type);
+		return -EINVAL;
+	}
+
+	if (mbus_config.flags & V4L2_MBUS_CSI2_1_LANE)
+		num_lanes = 1;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_2_LANE)
+		num_lanes = 2;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_3_LANE)
+		num_lanes = 3;
+	else if (mbus_config.flags & V4L2_MBUS_CSI2_4_LANE)
+		num_lanes = 4;
+
+	if (num_lanes > priv->lanes) {
+		dev_err(priv->dev,
+			"Unsupported mbus config: too many data lanes %u\n",
+			num_lanes);
+		return -EINVAL;
+	}
+
+	priv->active_lanes = num_lanes;
+
+	return 0;
+}
+
 static int rcsi2_start_receiver(struct rcar_csi2 *priv)
 {
 	const struct rcar_csi2_format *format;
@@ -490,6 +538,11 @@ static int rcsi2_start_receiver(struct rcar_csi2 *priv)
 	/* Code is validated in set_fmt. */
 	format = rcsi2_code_to_fmt(priv->mf.code);
 
+	/* Get the remote mbus config to get the number of enabled lanes. */
+	ret = rcsi2_config_active_lanes(priv);
+	if (ret)
+		return ret;
+
 	/*
 	 * Enable all supported CSI-2 channels with virtual channel and
 	 * data type matching.
@@ -522,7 +575,7 @@ static int rcsi2_start_receiver(struct rcar_csi2 *priv)
 	}
 
 	phycnt = PHYCNT_ENABLECLK;
-	phycnt |= (1 << priv->lanes) - 1;
+	phycnt |= (1 << priv->active_lanes) - 1;
 
 	mbps = rcsi2_calc_mbps(priv, format->bpp);
 	if (mbps < 0)
@@ -748,6 +801,7 @@ static int rcsi2_notify_bound(struct v4l2_async_notifier *notifier,
 	}
 
 	priv->remote = subdev;
+	priv->remote_pad = pad;
 
 	dev_dbg(priv->dev, "Bound %s pad: %d\n", subdev->name, pad);
 
@@ -793,6 +847,7 @@ static int rcsi2_parse_v4l2(struct rcar_csi2 *priv,
 			priv->lanes);
 		return -EINVAL;
 	}
+	priv->active_lanes = priv->lanes;
 
 	for (i = 0; i < ARRAY_SIZE(priv->lane_swap); i++) {
 		priv->lane_swap[i] = i < priv->lanes ?
-- 
2.26.2