media: tc358743: fix connected/active CSI-2 lane reporting

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------

g_mbus_config was supposed to indicate all supported lane numbers, not
only the number of those currently in active use. Since the TC358743
can dynamically reduce the number of active lanes if the required
bandwidth allows for it, report all lane numbers up to the connected
number of lanes as supported in pdata mode.
In device tree mode, do not report lane count and clock mode at all, as
the receiver driver can determine these from the device tree.

To allow communicating the number of currently active lanes, add a new
bitfield to the v4l2_mbus_config flags. This is a temporary fix, to be
used only until a better solution is found.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/media/i2c/tc358743.c

@@ -1609,11 +1609,20 @@ static int tc358743_get_mbus_config(struct v4l2_subdev *sd,
 				    struct v4l2_mbus_config *cfg)
 {
 	struct tc358743_state *state = to_state(sd);
+	const u32 mask = V4L2_MBUS_CSI2_LANE_MASK;
+
+	if (state->csi_lanes_in_use > state->bus.num_data_lanes)
+		return -EINVAL;
 
 	cfg->type = V4L2_MBUS_CSI2_DPHY;
+	cfg->flags = (state->csi_lanes_in_use << __ffs(mask)) & mask;
+
+	/* In DT mode, only report the number of active lanes */
+	if (sd->dev->of_node)
+		return 0;
 
-	/* Support for non-continuous CSI-2 clock is missing in the driver */
-	cfg->flags = V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
+	/* Support for non-continuous CSI-2 clock is missing in pdate mode */
+	cfg->flags |= V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
 
 	switch (state->csi_lanes_in_use) {
 	case 1:
@@ -2055,6 +2064,7 @@ static int tc358743_probe(struct i2c_client *client)
 	if (pdata) {
 		state->pdata = *pdata;
 		state->bus.flags = V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
+		state->bus.num_data_lanes = 4;
 	} else {
 		err = tc358743_probe_of(state);
 		if (err == -ENODEV)

include/media/v4l2-mediabus.h

@@ -92,6 +92,14 @@
 					 V4L2_MBUS_CSI2_CHANNEL_1 | \
 					 V4L2_MBUS_CSI2_CHANNEL_2 | \
 					 V4L2_MBUS_CSI2_CHANNEL_3)
+/*
+ * Number of lanes in use, 0 == use all available lanes (default)
+ *
+ * This is a temporary fix for devices that need to reduce the number of active
+ * lanes for certain modes, until g_mbus_config() can be replaced with a better
+ * solution.
+ */
+#define V4L2_MBUS_CSI2_LANE_MASK                (0xf << 10)
 
 /**
  * enum v4l2_mbus_type - media bus type