Moi,
On Fri, Dec 20, 2024 at 02:59:39PM +0200, Tomi Valkeinen wrote:
> Hi,
>
> On 17/12/2024 23:54, Sakari Ailus wrote:
> > Add link_freq field to struct v4l2_mbus_config in order to pass the link
> > frequency to the receiving sub-device.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-common.c | 15 +++++++++++++--
> > include/media/v4l2-mediabus.h | 2 ++
> > 2 files changed, 15 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> > index 9fe74c7e064f..e4b2de3833ee 100644
> > --- a/drivers/media/v4l2-core/v4l2-common.c
> > +++ b/drivers/media/v4l2-core/v4l2-common.c
> > @@ -508,12 +508,23 @@ EXPORT_SYMBOL_GPL(__v4l2_get_link_freq_ctrl);
> > s64 __v4l2_get_link_freq_pad(struct media_pad *pad, unsigned int mul,
> > unsigned int div)
> > {
> > + struct v4l2_mbus_config mbus_config = {};
> > struct v4l2_subdev *sd;
> > + int ret;
> > sd = media_entity_to_v4l2_subdev(pad->entity);
> > - if (!sd)
> > - return -ENODEV;
> > + ret = v4l2_subdev_call(sd, pad, get_mbus_config, pad->index,
> > + &mbus_config);
> > + if (ret < 0 && ret != -ENOIOCTLCMD)
> > + return ret;
> > +
> > + if (mbus_config.link_freq)
> > + return mbus_config.link_freq;
> > + /*
> > + * Fall back to using the link frequency control if the media bus config
> > + * doesn't provide a link frequency.
> > + */
> > return __v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div);
> > }
> > EXPORT_SYMBOL_GPL(__v4l2_get_link_freq_pad);
> > diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h
> > index e7f019f68c8d..24c738cd7894 100644
> > --- a/include/media/v4l2-mediabus.h
> > +++ b/include/media/v4l2-mediabus.h
> > @@ -169,6 +169,7 @@ enum v4l2_mbus_type {
> > /**
> > * struct v4l2_mbus_config - media bus configuration
> > * @type: interface type
> > + * @link_freq: The link frequency. See also V4L2_CID_LINK_FREQ control.
> > * @bus: bus configuration data structure
> > * @bus.parallel: embedded &struct v4l2_mbus_config_parallel.
> > * Used if the bus is parallel or BT.656.
> > @@ -183,6 +184,7 @@ enum v4l2_mbus_type {
> > */
> > struct v4l2_mbus_config {
> > enum v4l2_mbus_type type;
> > + u64 link_freq;
> > union {
> > struct v4l2_mbus_config_parallel parallel;
> > struct v4l2_mbus_config_mipi_csi1 mipi_csi1;
>
> Maybe the docs (V4L2_CID_LINK_FREQ and/or struct v4l2_mbus_config?) should
> mention that only if v4l2_mbus_config.link_freq is == 0, V4L2_CID_LINK_FREQ
> is used. Or, in other words, the driver must only use one of those methods.
Such documentation is added by the 3rd patch ("media: Documentation: Update link frequency driver
documentation"):
diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst
index c71003f74b1c..6f9eba189a9f 100644
--- a/Documentation/driver-api/media/tx-rx.rst
+++ b/Documentation/driver-api/media/tx-rx.rst
@@ -49,6 +49,10 @@ Link frequency
The :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` control is used to tell the
receiver the frequency of the bus (i.e. it is not the same as the symbol rate).
+Drivers that do not have user-configurable link frequency should report it
+through the ``.get_mbus_config()`` subdev pad operation, in the ``link_freq``
+field of struct v4l2_mbus_config, instead of through controls.
+
``.enable_streams()`` and ``.disable_streams()`` callbacks
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
--
Sakari Ailus
