On 07/05/2020 16:35, Jacopo Mondi wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> While normal video/radio/vbi/swradio nodes have a proper QUERYCAP ioctl
> that apps can call to determine that it is indeed a V4L2 device, there
> is currently no equivalent for v4l-subdev nodes. Adding this ioctl will
> solve that, and it will allow utilities like v4l2-compliance to be used
> with these devices as well.
>
> SUBDEV_QUERYCAP currently returns the version and subdev_caps of the
> subdevice. Define as the initial set of subdev_caps the read-only or
> read/write flags, to signal to userspace which set of IOCTLs are
> available on the subdevice.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-subdev.c | 12 ++++++++++++
> include/uapi/linux/v4l2-subdev.h | 18 ++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 174778f9c0bc4..6ae617a1e7e78 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -15,6 +15,7 @@
> #include <linux/types.h>
> #include <linux/videodev2.h>
> #include <linux/export.h>
> +#include <linux/version.h>
>
> #include <media/v4l2-ctrls.h>
> #include <media/v4l2-device.h>
> @@ -344,6 +345,17 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
> int rval;
>
> switch (cmd) {
> + case VIDIOC_SUBDEV_QUERYCAP: {
> + struct v4l2_subdev_capability *cap = arg;
> +
> + memset(cap->reserved, 0, sizeof(cap->reserved));
> + cap->version = LINUX_VERSION_CODE;
> + cap->capabilities = ro_subdev ? V4L2_SUBDEV_CAP_RO_SUBDEV
> + : V4L2_SUBDEV_CAP_RW_SUBDEV;
> +
> + return 0;
> + }
> +
> case VIDIOC_QUERYCTRL:
> /*
> * TODO: this really should be folded into v4l2_queryctrl (this
> diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> index 03970ce307419..29d1874cb5e95 100644
> --- a/include/uapi/linux/v4l2-subdev.h
> +++ b/include/uapi/linux/v4l2-subdev.h
> @@ -155,9 +155,27 @@ struct v4l2_subdev_selection {
> __u32 reserved[8];
> };
>
> +/**
> + * struct v4l2_subdev_capability - subdev capabilities
> + * @version: the driver versioning number
> + * @capabilities: the subdev capabilities, see V4L2_SUBDEV_CAP_*
> + * @reserved: for future use, set to zero for now
> + */
> +struct v4l2_subdev_capability {
> + __u32 version;
> + __u32 capabilities;
> + __u32 reserved[14];
> +};
> +
> +/* The v4l2 sub-device video device node is registered in read-only mode. */
> +#define V4L2_SUBDEV_CAP_RO_SUBDEV BIT(0)
> +/* The v4l2 sub-device video device node is registered in read/write mode. */
> +#define V4L2_SUBDEV_CAP_RW_SUBDEV BIT(1)
Huh? Read-write is the default, so why create a capability for that? Just drop
this cap. If bit RO_SUBDEV is set, then this is read-only, otherwise it is read-write.
Makes perfect sense.
Otherwise this series looks good, so a v7 that removes V4L2_SUBDEV_CAP_RW_SUBDEV
should be ready for a pull request.
Regards,
Hans
> +
> /* Backwards compatibility define --- to be removed */
> #define v4l2_subdev_edid v4l2_edid
>
> +#define VIDIOC_SUBDEV_QUERYCAP _IOR('V', 0, struct v4l2_subdev_capability)
> #define VIDIOC_SUBDEV_G_FMT _IOWR('V', 4, struct v4l2_subdev_format)
> #define VIDIOC_SUBDEV_S_FMT _IOWR('V', 5, struct v4l2_subdev_format)
> #define VIDIOC_SUBDEV_G_FRAME_INTERVAL _IOWR('V', 21, struct v4l2_subdev_frame_interval)
> --
> 2.26.1
>
