linux-kernel - Re: [PATCH 2/2] usb: webcam: Invalid size of Processing Unit Descriptor

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Date:   Sun, 14 Mar 2021 04:30:06 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Pawel Laszczak <pawell@...ence.com>
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org,
        linux-api@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, peter.chen@...nel.org,
        kurahul@...ence.com
Subject: Re: [PATCH 2/2] usb: webcam: Invalid size of Processing Unit
 Descriptor

Hi Pawel,

Thank you for the patch.

On Mon, Mar 08, 2021 at 11:27:35AM +0100, Pawel Laszczak wrote:
> From: Pawel Laszczak <pawell@...ence.com>
> 
> According with USB Device Class Definition for Video Device the
> Processing Unit Descriptor bLength should be 12 (10 + bmControlSize),
> but it has 11.
> 
> Invalid length caused that Processing Unit Descriptor Test Video form
> CV tool failed. To fix this issue patch adds bmVideoStandards into
> uvc_processing_unit_descriptor structure.

The bmVideoStandards field was added in UVC 1.1, it wasn't part of UVC
1.0a. The commit message should explain this.

This change looks good to me, but could you also update
drivers/usb/gadget/legacy/webcam.c and
drivers/usb/gadget/function/f_uvc.c to explicitly set this field to 0 ?

With that,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> ---
>  include/uapi/linux/usb/video.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/include/uapi/linux/usb/video.h b/include/uapi/linux/usb/video.h
> index d854cb19c42c..2a54e8fdd341 100644
> --- a/include/uapi/linux/usb/video.h
> +++ b/include/uapi/linux/usb/video.h
> @@ -302,6 +302,7 @@ struct uvc_processing_unit_descriptor {
>  	__u8   bControlSize;
>  	__u8   bmControls[2];
>  	__u8   iProcessing;
> +	__u8   bmVideoStandards;
>  } __attribute__((__packed__));
>  
>  #define UVC_DT_PROCESSING_UNIT_SIZE(n)			(9+(n))

-- 
Regards,

Laurent Pinchart