On 07/28/2017 04:04 PM, Hans Verkuil wrote:
> On 07/28/2017 03:25 PM, Laurent Pinchart wrote:
>> To solve this, if you really want to identify the type of device node at
>> runtime, we should have a single ioctl supported by the two device nodes.
>> Given that we"re running out of capabilities bits for VIDIOC_QUERYCAP, this
>> could be a good occasion to introduce a new ioctl to query capabilities.
>
> This makes more sense :-)
Here is a quick proposal:
struct v4l2_ext_capability {
char driver[16];
char name[32];
char bus_info[32];
__u64 device_caps;
__u32 version;
__u32 entity_id;
/* Corresponding media controller device node specifications */
__u32 media_node_major;
__u32 media_node_minor;
__u32 reserved[16];
};
#define V4L2_CAP_SUBDEV 0x00000008 /* This is a v4l-subdev device */
#define V4L2_CAP_ENTITY 0x08000000 /* MC entity */
#define VIDIOC_EXT_QUERYCAP _IOR('V', 104, struct v4l2_ext_capability)
We keep the existing caps, but double the size of the device_caps field.
Add a CAP_SUBDEV to indicate that it is a subdev, and a CAP_ENTITY to indicate
that it is part of the media controller.
I dropped the old 'capabilities' field. In V4L2 that is meant to give the sum
of all the capabilities of all the video/vbi/radio/swradio device nodes, but
it never worked and is inconsistently implemented.
It's really historical so I decided to drop it. I also replaced __u8 by char
for the string fields (__u8 was very, very annoying!).
No driver changes needed for this, it can all be handled in the core.
Regards,
Hans
