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Message-ID: <20250903102243.1563527-2-isaac.scott@ideasonboard.com>
Date: Wed, 3 Sep 2025 11:22:40 +0100
From: Isaac Scott <isaac.scott@...asonboard.com>
To: laurent.pinchart@...asonboard.com
Cc: rmfrfs@...il.com,
martink@...teo.de,
kernel@...i.sm,
mchehab@...nel.org,
shawnguo@...nel.org,
s.hauer@...gutronix.de,
kernel@...gutronix.de,
festevam@...il.com,
linux-media@...r.kernel.org,
imx@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
hverkuil@...nel.org,
nicolas.dufresne@...labora.com,
sakari.ailus@...ux.intel.com,
tomi.valkeinen@...asonboard.com,
jonas@...boo.se,
dan.scally+renesas@...asonboard.com,
m.szyprowski@...sung.com,
mehdi.djait@...ux.intel.com,
niklas.soderlund+renesas@...natech.se,
Isaac Scott <isaac.scott@...asonboard.com>
Subject: [PATCH v2 1/3] 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 number
of data lanes specified in device tree.
Signed-off-by: Isaac Scott <isaac.scott@...asonboard.com>
---
drivers/media/v4l2-core/v4l2-common.c | 25 +++++++++++++++++++++++++
include/media/v4l2-common.h | 1 +
2 files changed, 26 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index 6e585bc76367..8683107b3704 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -571,6 +571,31 @@ s64 __v4l2_get_link_freq_pad(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_pad);
+
+unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad, unsigned int dt_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;
+
+ if (!mbus_config.bus.mipi_csi2.num_data_lanes)
+ return dt_lanes;
+
+ lanes = mbus_config.bus.mipi_csi2.num_data_lanes;
+
+ if (lanes < 0 || lanes > dt_lanes)
+ return -EINVAL;
+
+ return lanes;
+}
+EXPORT_SYMBOL_GPL(v4l2_get_active_data_lanes);
#endif /* CONFIG_MEDIA_CONTROLLER */
/*
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index 0a43f56578bc..3f8937260c76 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -584,6 +584,7 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
(pad, mul, div)
s64 __v4l2_get_link_freq_pad(struct media_pad *pad, unsigned int mul,
unsigned int div);
+unsigned int v4l2_get_active_data_lanes(const struct media_pad *pad, unsigned int dt_lanes);
#else
#define v4l2_get_link_freq(handler, mul, div) \
__v4l2_get_link_freq_ctrl(handler, mul, div)
--
2.43.0
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