Sometimes, users will not use all of the MIPI CSI 2 lanes available when
connecting to the MIPI CSI receiver of their device. Add a helper
function that checks the mbus_config for the device driver to allow
users to define the number of active data lanes through the
get_mbus_config op.
If the driver does not implement this op, fall back to using the maximum
number of lanes available.
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
---
drivers/media/v4l2-core/v4l2-common.c | 29 +++++++++++++++++++++++++++++
include/media/v4l2-common.h | 20 ++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index b367d479d6b3..2b4cec25e751 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -573,6 +573,35 @@ s64 v4l2_get_link_freq(const struct media_pad *pad, unsigned int mul,
return v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div);
}
EXPORT_SYMBOL_GPL(v4l2_get_link_freq);
+
+unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad,
+ unsigned int max_data_lanes)
+{
+ struct v4l2_mbus_config mbus_config = {};
+ struct v4l2_subdev *sd;
+ unsigned int lanes;
+ int ret;
+
+ sd = media_entity_to_v4l2_subdev(pad->entity);
+ ret = v4l2_subdev_call(sd, pad, get_mbus_config, pad->index,
+ &mbus_config);
+ if (ret < 0 && ret != -ENOIOCTLCMD)
+ return ret;
+
+ /* This relies on the mbus_config being zeroed at init time */
+ lanes = mbus_config.bus.mipi_csi2.num_data_lanes;
+ if (!lanes)
+ return max_data_lanes;
+
+ if (lanes > max_data_lanes) {
+ dev_dbg(sd->dev, "Active data lanes (%u) exceeds max (%u)\n",
+ lanes, max_data_lanes);
+ return -EINVAL;
+ }
+
+ return lanes;
+}
+EXPORT_SYMBOL_GPL(v4l2_get_active_data_lanes);
#endif
/*
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index 5c0a7f6b5bb6..950df46cb27a 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -581,6 +581,26 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
#ifdef CONFIG_MEDIA_CONTROLLER
s64 v4l2_get_link_freq(const struct media_pad *pad, unsigned int mul,
unsigned int div);
+
+/**
+ * v4l2_get_active_data_lanes - Get number of active data lanes from driver
+ *
+ * @pad: The transmitter's media pad.
+ * @max_data_lanes: The maximum number of active data lanes supported by
+ * the MIPI CSI link in hardware.
+ *
+ * This function is intended for obtaining the number of data lanes that are
+ * actively being used by the driver for a MIPI CSI-2 device on a given media pad.
+ * This information is derived from a mbus_config fetched from a device driver
+ * using the get_mbus_config v4l2_subdev pad op.
+ *
+ * Return:
+ * * >0: Number of active data lanes
+ * * %-EINVAL: Number of active data lanes is invalid, as it exceeds the maximum
+ * supported data lanes.
+ */
+unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad,
+ unsigned int max_data_lanes);
#endif
void v4l2_simplify_fraction(u32 *numerator, u32 *denominator,
--
2.43.0