On 14/07/2020 15:58, Jacopo Mondi wrote:
> Introduce two new pad operations to allow retrieving and configuring the
> media bus parameters on a subdevice pad.
>
> The newly introduced operations aims to replace the s/g_mbus_config video
> operations, which have been on their way for deprecation since a long
> time.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> include/media/v4l2-subdev.h | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index f7fe78a6f65a..d8b9d5735307 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -670,6 +670,29 @@ struct v4l2_subdev_pad_config {
> *
> * @set_frame_desc: set the low level media bus frame parameters, @fd array
> * may be adjusted by the subdev driver to device capabilities.
> + *
> + * @get_mbus_config: get the media bus configuration of a remote sub-device.
> + * The media bus configuration is usually retrieved from the
> + * firmware interface at sub-device probe time, immediately
> + * applied to the hardware and eventually adjusted by the
> + * driver. Remote sub-devices (usually video receivers) shall
> + * use this operation to query the transmitting end bus
> + * configuration in order to adjust their own one accordingly.
> + * Callers should make sure they get the most up-to-date as
> + * possible configuration from the remote end, likely calling
> + * this operation as close as possible to stream on time. The
> + * operation shall fail if the pad index it has been called on
> + * is not valid.
> + *
> + * @set_mbus_config: set the media bus configuration of a remote sub-device.
> + * This operations is intended to allow, in combination with
> + * the get_mbus_config operation, the negotiation of media bus
> + * configuration parameters between media sub-devices. The
> + * operation shall not fail if the requested configuration is
> + * not supported, but the driver shall update the content of
> + * the %config argument to reflect what has been actually
> + * applied to the hardware. The operation shall fail if the
> + * pad index it has been called on is not valid.
> */
Hm, I'd hoped I could merge this, but I think include/media/v4l2-mediabus.h
also needs to be updated.
So the old g_mbus_config returned all supported configurations, while the
new get_mbus_config returns the *current* configuration.
That's fine, but that means that the meaning of the struct v4l2_mbus_config
flags field changes as well and several comments in v4l2-mediabus.h need to
be updated to reflect this.
E.g. instead of '/* How many lanes the client can use */' it becomes
'/* How many lanes the client uses */'.
Frankly, these flags can be redesigned now since you only need a single
e.g. V4L2_MBUS_HSYNC_ACTIVE_HIGH flag since if it is not set, then that
means ACTIVE_LOW. And since it is now a single bit, it is also easy to
make each flag a bit field.
The CSI2 lanes/channels can just be a bit field for the number of lanes/channels,
which is much easier to read. I strongly recommend making this change at the minimum.
Now all this can be done in a follow-up series, but the v4l2-mediabus.h
definitely needs to be updated to reflect the new code.
This can be done as a v6 5.5/9 patch (since it should come right after the
g/s_mbus_config removal).
Regards,
Hans
> struct v4l2_subdev_pad_ops {
> int (*init_cfg)(struct v4l2_subdev *sd,
> @@ -710,6 +733,10 @@ struct v4l2_subdev_pad_ops {
> struct v4l2_mbus_frame_desc *fd);
> int (*set_frame_desc)(struct v4l2_subdev *sd, unsigned int pad,
> struct v4l2_mbus_frame_desc *fd);
> + int (*get_mbus_config)(struct v4l2_subdev *sd, unsigned int pad,
> + struct v4l2_mbus_config *config);
> + int (*set_mbus_config)(struct v4l2_subdev *sd, unsigned int pad,
> + struct v4l2_mbus_config *config);
> };
>
> /**
>
