linux-kernel - Re: [PATCH v2 2/3] usb: gadget: f_fs: add ioctl returning ep descriptor

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Date:	Fri, 25 Jul 2014 16:15:49 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Robert Baldyga <r.baldyga@...sung.com>, balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
	andrzej.p@...sung.com, Robert Baldyga <r.baldyga@...sung.com>
Subject: Re: [PATCH v2 2/3] usb: gadget: f_fs: add ioctl returning ep descriptor

On Fri, Jul 25 2014, Robert Baldyga wrote:
> This patch introduces ioctl named FUNCTIONFS_ENDPOINT_DESC, which
> returns endpoint descriptor to userspace. It works only if function
> is active.

I would argue that user space should never need to know the real
descriptor.  Is this ioctl needed for anything in particular?

>
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
> ---
>  drivers/usb/gadget/f_fs.c           | 17 +++++++++++++++++
>  include/uapi/linux/usb/functionfs.h |  6 ++++++
>  2 files changed, 23 insertions(+)
>
> diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
> index 490b30f..a2e18cc 100644
> --- a/drivers/usb/gadget/f_fs.c
> +++ b/drivers/usb/gadget/f_fs.c
> @@ -1031,6 +1031,23 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
>  		case FUNCTIONFS_ENDPOINT_REVMAP:
>  			ret = epfile->ep->num;
>  			break;
> +		case FUNCTIONFS_ENDPOINT_DESC:
> +		{
> +			int desc_idx;
> +			struct usb_endpoint_descriptor *desc;
> +
> +			if (epfile->ffs->gadget->speed == USB_SPEED_SUPER)
> +				desc_idx = 2;
> +			else if (epfile->ffs->gadget->speed == USB_SPEED_HIGH)
> +				desc_idx = 1;
> +			else
> +				desc_idx = 0;
> +			desc = epfile->ep->descs[desc_idx];
> +			ret = copy_to_user((void *)value, desc, sizeof(*desc));
> +			if (ret)
> +				ret = -EFAULT;
> +			break;
> +		}
>  		default:
>  			ret = -ENOTTY;
>  		}
> diff --git a/include/uapi/linux/usb/functionfs.h b/include/uapi/linux/usb/functionfs.h
> index 1dc473a..1ab6f06 100644
> --- a/include/uapi/linux/usb/functionfs.h
> +++ b/include/uapi/linux/usb/functionfs.h
> @@ -197,6 +197,12 @@ struct usb_functionfs_event {
>   */
>  #define	FUNCTIONFS_ENDPOINT_REVMAP	_IO('g', 129)
>  
> +/*
> + * Returns endpoint descriptor. In funciton is not active returns -ENODEV.
> + */
> +#define	FUNCTIONFS_ENDPOINT_DESC	_IOR('g', 130, \
> +					     struct usb_endpoint_descriptor)
> +
>  
>  
>  #endif /* _UAPI__LINUX_FUNCTIONFS_H__ */
> -- 
> 1.9.1
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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