From fd3f646e1c9d783d1f4ef30e5376ccf315a8ae30 Mon Sep 17 00:00:00 2001 From: Isaac Scott Date: Wed, 29 Oct 2025 18:03:18 +0000 Subject: media: v4l: Add helper to get number of active lanes via a pad 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 Reviewed-by: Laurent Pinchart Signed-off-by: Isaac Scott Signed-off-by: Sakari Ailus Signed-off-by: Hans Verkuil --- drivers/media/v4l2-core/v4l2-common.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'drivers/media/v4l2-core/v4l2-common.c') diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c index b367d479d6b3..554c591e1113 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); + +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 /* -- cgit v1.2.3