Re: [PATCH RFC 2/2] staging: vc04_services: Document VCHIQ character device

Greg Kroah-Hartman
2025-05-21T11:20:57Z

On Sat, May 10, 2025 at 12:11:52AM +0200, Stefan Wahren wrote:
> From: Phil Elwell <phil@raspberrypi.com>
>
> Document the IOCTLs for the VCHIQ character device, which provide
> a userspace interface to access the VideoCore VPU of the
> Raspberry Pi. Several ARM side libraries make use of it like EGL,
> MMAL and OpenMAX.
>
> Link: https://github.com/raspberrypi/linux/pull/6801
> Signed-off-by: Phil Elwell <phil@raspberrypi.com>
> [wahrenst@gmx.net: Rewrite commit log]
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
> ---
> .../vc04_services/Documentation/vchiq-cdev | 87 +++++++++++++++++++
> 1 file changed, 87 insertions(+)
> create mode 100644 drivers/staging/vc04_services/Documentation/vchiq-cdev
>
> diff --git a/drivers/staging/vc04_services/Documentation/vchiq-cdev b/drivers/staging/vc04_services/Documentation/vchiq-cdev
> new file mode 100644
> index 000000000000..99ab2567643e
> --- /dev/null
> +++ b/drivers/staging/vc04_services/Documentation/vchiq-cdev
> @@ -0,0 +1,87 @@
> +What: /dev/vchiq
> +Date: October 2016
> +KernelVersion: 4.9
> +Contact: kernel-list@raspberrypi.com
> +Description:
> + The ioctl interface for the VCHIQ character device.
> + Following actions are supported:
> +
> + * VCHIQ_IOC_CONNECT:
> + Establish/confirm the link to the VPU peer.

I understand the need, but this does not document the parameters to the
ioctls, so it's not all that useful. How about just a normal
documentation file with this all written out?

thanks,

greg k-h