Re: [PATCH 1/7] usb: gadget: uvc: consistently use define for headerlen

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Michael,

Thank you for the patch.

On Thu, Sep 30, 2021 at 12:27:11PM +0200, Michael Grzeschik wrote:
> The uvc request headerlen of 2 was defined as UVCG_REQUEST_HEADER_LEN
> in commit e81e7f9a0eb9 ("usb: gadget: uvc: add scatter gather support").
> We missed to use it consistently. This patch fixes that.
> 
> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> ---
>  drivers/usb/gadget/function/uvc_video.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
> index b4a763e5f70e1..da93b46df464d 100644
> --- a/drivers/usb/gadget/function/uvc_video.c
> +++ b/drivers/usb/gadget/function/uvc_video.c
> @@ -302,7 +302,9 @@ uvc_video_alloc_requests(struct uvc_video *video)
>  		list_add_tail(&video->ureq[i].req->list, &video->req_free);
>  		/* req_size/PAGE_SIZE + 1 for overruns and + 1 for header */
>  		sg_alloc_table(&video->ureq[i].sgt,
> -			       DIV_ROUND_UP(req_size - 2, PAGE_SIZE) + 2,
> +			       DIV_ROUND_UP(req_size - UVCG_REQUEST_HEADER_LEN,

This is correct, we remove the header size.

> +					    PAGE_SIZE) +
> +			       UVCG_REQUEST_HEADER_LEN,

But here we add two entries to the sgt, not two bytes (see the above
comment), so it's unrelated to the header size.

>  			       GFP_KERNEL);
>  	}
>  

-- 
Regards,

Laurent Pinchart