Hi Laurent, On Sun, Dec 15, 2024 at 06:59:35PM +0200, Laurent Pinchart wrote: > Hi Sakari, > > Thank you for the patch. > > On Tue, Dec 10, 2024 at 09:59:03AM +0200, Sakari Ailus wrote: > > Add link_freq field to struct v4l2_mbus_config in order to pass the link > > frequency to the receiving sub-device. > > The documentation of v4l2_get_link_freq() should be expanded to explain > the new mode of operation. It should document which of the supported > methods are recommended for new drivers. > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > --- > > drivers/media/v4l2-core/v4l2-common.c | 11 ++++++++--- > > include/media/v4l2-mediabus.h | 2 ++ > > 2 files changed, 10 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c > > index 9fe74c7e064f..88fbd5608f00 100644 > > --- a/drivers/media/v4l2-core/v4l2-common.c > > +++ b/drivers/media/v4l2-core/v4l2-common.c > > @@ -508,13 +508,18 @@ 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 = {}; > > Isn't mbus_config fully populated by the .get_mbus_config() operation ? > That should be documented in the .get_mbus_config() operation > documentation. It's a good practice to zero the memory before drivers get to work on it. I presume drivers will set the fields that are relevant for them and ignore the rest. I can add a note on get_mbus_config() the drivers should set all struct fields to known values. > > > 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; > > > > - return __v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div); > > + return mbus_config.link_freq ?: > > + __v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div); > > if (mbus_config.link_freq) > return mbus_config.link_freq; > > return __v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div); Whether this would be cleaner is debatable at least. I can switch if you insist though. > > I wonder if we should also add a message in case link_freq is 0, to get > drivers to convert to reporting the link frequency through > .get_mbus_config() if they already implement the operation. I'm not sure this will be useful: in most cases the LINK_FREQ control is used and for a reason: it's user-configurable. Drivers should only populate the field if the link frequency is determined by the driver. For the receiver drivers it does not matter: they use v4l2_get_link_freq(). > > > } > > EXPORT_SYMBOL_GPL(__v4l2_get_link_freq_pad); > > #endif /* CONFIG_MEDIA_CONTROLLER */ > > diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h > > index 5bce6e423e94..cc5f776dc662 100644 > > --- a/include/media/v4l2-mediabus.h > > +++ b/include/media/v4l2-mediabus.h > > @@ -148,6 +148,7 @@ 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. > > Not a candidate for this series, but I'd like to simplify drivers by > implementing the LINK_FREQ control automatically. > > > * @bus: bus configuration data structure > > * @bus.parallel: embedded &struct v4l2_mbus_config_parallel. > > * Used if the bus is parallel or BT.656. > > @@ -162,6 +163,7 @@ 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; > -- Regards, Sakari Ailus