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Message-ID: <3292baba-26d5-16b2-de45-054fee803f0a@ti.com>
Date: Thu, 9 Mar 2017 11:34:00 +0200
From: Roger Quadros <rogerq@...com>
To: <laurent.pinchart@...asonboard.com>, <balbi@...nel.org>
CC: <b-liu@...com>, <nsekhar@...com>, <linux-usb@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] usb: gadget: f_uvc: Fix SuperSpeed companion
descriptor's wBytesPerInterval
Felipe,
On 08/03/17 16:05, Roger Quadros wrote:
> The streaming_maxburst module parameter is 0 offset (0..15)
> so we must add 1 while using it for wBytesPerInterval
> calculation for the SuperSpeed companion descriptor.
>
> Without this host uvcvideo driver will always see the wrong
> wBytesPerInterval for SuperSpeed uvc gadget and may not find
> a suitable video interface endpoint.
> e.g. for streaming_maxburst = 0 case it will always
> fail as wBytePerInterval was evaluating to 0.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Roger Quadros <rogerq@...com>
Please pick this one for v4.11-rc with Laurent's Reviewed-by. Thanks.
> ---
> drivers/usb/gadget/function/f_uvc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
> index 29b41b5..c7689d0 100644
> --- a/drivers/usb/gadget/function/f_uvc.c
> +++ b/drivers/usb/gadget/function/f_uvc.c
> @@ -625,7 +625,7 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
> uvc_ss_streaming_comp.bMaxBurst = opts->streaming_maxburst;
> uvc_ss_streaming_comp.wBytesPerInterval =
> cpu_to_le16(max_packet_size * max_packet_mult *
> - opts->streaming_maxburst);
> + (opts->streaming_maxburst + 1));
>
> /* Allocate endpoints. */
> ep = usb_ep_autoconfig(cdev->gadget, &uvc_control_ep);
>
--
cheers,
-roger
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