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

Greg Kroah-Hartman gregkh at linuxfoundation.org
Wed May 21 04:20:54 PDT 2025


On Sat, May 10, 2025 at 12:11:52AM +0200, Stefan Wahren wrote:
> From: Phil Elwell <phil at 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 at raspberrypi.com>
> [wahrenst at gmx.net: Rewrite commit log]
> Signed-off-by: Stefan Wahren <wahrenst at 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 at 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



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