Re: [RFCv11 PATCH 08/29] videodev2.h: add request_fd field to v4l2_ext_controls

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Mon,  9 Apr 2018 16:20:05 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> From: Alexandre Courbot <acourbot@chromium.org>
> 
> If which is V4L2_CTRL_WHICH_REQUEST, then the request_fd field can be
> used to specify a request for the G/S/TRY_EXT_CTRLS ioctls.

That's a general comment that applies not only to this patch, but to
all patches touching include/uapi:

Please, for v12, add also the required Documentation/ changes together
with the patch that introduces the new field.

That makes a lot easier to understand why this would be needed. Also,
in the future, if someone needs to look at the git history, it makes
a way easier to identify what parts of the API got introduced by each
patch.

> 
> Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
> ---
>  drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 5 ++++-
>  drivers/media/v4l2-core/v4l2-ioctl.c          | 6 +++---
>  include/uapi/linux/videodev2.h                | 4 +++-
>  3 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> index 5198c9eeb348..0782b3666deb 100644
> --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> @@ -732,7 +732,8 @@ struct v4l2_ext_controls32 {
>  	__u32 which;
>  	__u32 count;
>  	__u32 error_idx;
> -	__u32 reserved[2];
> +	__s32 request_fd;
> +	__u32 reserved[1];
>  	compat_caddr_t controls; /* actually struct v4l2_ext_control32 * */
>  };
>  
> @@ -807,6 +808,7 @@ static int get_v4l2_ext_controls32(struct file *file,
>  	    get_user(count, &up->count) ||
>  	    put_user(count, &kp->count) ||
>  	    assign_in_user(&kp->error_idx, &up->error_idx) ||
> +	    assign_in_user(&kp->request_fd, &up->request_fd) ||
>  	    copy_in_user(kp->reserved, up->reserved, sizeof(kp->reserved)))
>  		return -EFAULT;
>  
> @@ -865,6 +867,7 @@ static int put_v4l2_ext_controls32(struct file *file,
>  	    get_user(count, &kp->count) ||
>  	    put_user(count, &up->count) ||
>  	    assign_in_user(&up->error_idx, &kp->error_idx) ||
> +	    assign_in_user(&up->request_fd, &kp->request_fd) ||
>  	    copy_in_user(up->reserved, kp->reserved, sizeof(up->reserved)) ||
>  	    get_user(kcontrols, &kp->controls))
>  		return -EFAULT;
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index f48c505550e0..9ce23e23c5bf 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -553,8 +553,8 @@ static void v4l_print_ext_controls(const void *arg, bool write_only)
>  	const struct v4l2_ext_controls *p = arg;
>  	int i;
>  
> -	pr_cont("which=0x%x, count=%d, error_idx=%d",
> -			p->which, p->count, p->error_idx);
> +	pr_cont("which=0x%x, count=%d, error_idx=%d, request_fd=%d",
> +			p->which, p->count, p->error_idx, p->request_fd);
>  	for (i = 0; i < p->count; i++) {
>  		if (!p->controls[i].size)
>  			pr_cont(", id/val=0x%x/0x%x",
> @@ -870,7 +870,7 @@ static int check_ext_ctrls(struct v4l2_ext_controls *c, int allow_priv)
>  	__u32 i;
>  
>  	/* zero the reserved fields */
> -	c->reserved[0] = c->reserved[1] = 0;
> +	c->reserved[0] = 0;
>  	for (i = 0; i < c->count; i++)
>  		c->controls[i].reserved2[0] = 0;
>  
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 600877be5c22..6f41baa53787 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1592,7 +1592,8 @@ struct v4l2_ext_controls {
>  	};
>  	__u32 count;
>  	__u32 error_idx;
> -	__u32 reserved[2];
> +	__s32 request_fd;
> +	__u32 reserved[1];
>  	struct v4l2_ext_control *controls;
>  };
>  
> @@ -1605,6 +1606,7 @@ struct v4l2_ext_controls {
>  #define V4L2_CTRL_MAX_DIMS	  (4)
>  #define V4L2_CTRL_WHICH_CUR_VAL   0
>  #define V4L2_CTRL_WHICH_DEF_VAL   0x0f000000
> +#define V4L2_CTRL_WHICH_REQUEST   0x0f010000
>  
>  enum v4l2_ctrl_type {
>  	V4L2_CTRL_TYPE_INTEGER	     = 1,



Thanks,
Mauro