linux-kernel - Re: [PATCH v7 2/5] usb: gadget: add quirk_ep_out_aligned_size field to struct usb

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Message-ID: <xa1t7gbdfn8c.fsf@mina86.com>
Date:	Tue, 10 Dec 2013 03:34:11 +0100
From:	Michal Nazarewicz <mina86@...a86.com>
To:	David Cohen <david.a.cohen@...ux.intel.com>, balbi@...com,
	gregkh@...uxfoundation.org
Cc:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	stern@...land.harvard.edu,
	David Cohen <david.a.cohen@...ux.intel.com>
Subject: Re: [PATCH v7 2/5] usb: gadget: add quirk_ep_out_aligned_size field to struct usb_gadget

dOn Tue, Dec 10 2013, David Cohen wrote:
> Due to USB controllers may have different restrictions, usb gadget layer
> needs to provide a generic way to inform gadget functions to complain
> with non-standard requirements.
>
> This patch adds 'quirk_ep_out_aligned_size' field to struct usb_gadget
> to inform when controller's epout requires buffer size to be aligned to
> MaxPacketSize. A helper is also provided to align buffer size when
> necessary.
>
> Signed-off-by: David Cohen <david.a.cohen@...ux.intel.com>
> Cc: Alan Stern <stern@...land.harvard.edu>
> Cc: Michal Nazarewicz <mina86@...a86.com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>

> ---
>  include/linux/usb/gadget.h | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index 23b3bfd0a842..cae8a6216551 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -502,6 +502,8 @@ struct usb_gadget_ops {
>   *	only supports HNP on a different root port.
>   * @b_hnp_enable: OTG device feature flag, indicating that the A-Host
>   *	enabled HNP support.
> + * @quirk_ep_out_aligned_size: epout requires buffer size to be aligned to
> + *	MaxPacketSize.
>   *
>   * Gadgets have a mostly-portable "gadget driver" implementing device
>   * functions, handling all usb configurations and interfaces.  Gadget
> @@ -541,6 +543,7 @@ struct usb_gadget {
>  	unsigned			b_hnp_enable:1;
>  	unsigned			a_hnp_support:1;
>  	unsigned			a_alt_hnp_support:1;
> +	unsigned			quirk_ep_out_aligned_size:1;
>  };
>  #define work_to_gadget(w)	(container_of((w), struct usb_gadget, work))
>  
> @@ -559,6 +562,23 @@ static inline struct usb_gadget *dev_to_usb_gadget(struct device *dev)
>  
>  
>  /**
> + * usb_ep_align_maybe - returns @len aligned to ep's maxpacketsize if gadget
> + *	requires quirk_ep_out_aligned_size, otherwise reguens len.

“returns”

> + * @g: controller to check for quirk
> + * @ep: the endpoint whose maxpacketsize is used to align @len
> + * @len: buffer size's length to align to @ep's maxpacketsize
> + *
> + * This helper is used in case it's required for any reason to check and maybe
> + * align buffer's size to an ep's maxpacketsize.
> + */
> +static inline size_t
> +usb_ep_align_maybe(struct usb_gadget *g, struct usb_ep *ep, size_t len)
> +{
> +	return !g->quirk_ep_out_aligned_size ? len :
> +			round_up(len, (size_t)ep->desc->wMaxPacketSize);
> +}
> +
> +/**
>   * gadget_is_dualspeed - return true iff the hardware handles high speed
>   * @g: controller that might support both high and full speeds
>   */

-- 
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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