linux-kernel - Re: [PATCH 1/9] usb: gadget: fix usb_ep_align_maybe endianness and new usb_ep

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Message-ID: <xa1tbn1i3m9k.fsf@mina86.com>
Date:	Wed, 27 Jul 2016 21:37:43 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	"Felipe F. Tonello" <eu@...ipetonello.com>,
	linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
	Baolin Wang <baolin.wang@...aro.org>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
Subject: Re: [PATCH 1/9] usb: gadget: fix usb_ep_align_maybe endianness and new usb_ep_align

On Tue, Jul 26 2016, Felipe F. Tonello wrote:
> USB spec specifies wMaxPacketSize to be little endian (as other properties),
> so when using this variable in the driver we should convert to the current
> CPU endianness if necessary.
>
> This patch also introduces usb_ep_align() which does always returns the
> aligned buffer size for an endpoint. This is useful to be used by USB requests
> allocator functions.
>
> Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>

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

> ---
>  include/linux/usb/gadget.h | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index 612dbdfa388e..b8fa6901b881 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -418,8 +418,20 @@ static inline struct usb_gadget *dev_to_usb_gadget(struct device *dev)
>  	list_for_each_entry(tmp, &(gadget)->ep_list, ep_list)
>  
>  /**
> + * usb_ep_align - returns @len aligned to ep's maxpacketsize.
> + * @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 to align buffer's size to an ep's maxpacketsize.
> + */
> +static inline size_t usb_ep_align(struct usb_ep *ep, size_t len)
> +{
> +	return round_up(len, (size_t)le16_to_cpu(ep->desc->wMaxPacketSize));
> +}
> +
> +/**
>   * usb_ep_align_maybe - returns @len aligned to ep's maxpacketsize if gadget
> - *	requires quirk_ep_out_aligned_size, otherwise reguens len.
> + *	requires quirk_ep_out_aligned_size, otherwise returns len.
>   * @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
> @@ -430,8 +442,7 @@ static inline struct usb_gadget *dev_to_usb_gadget(struct device *dev)
>  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);
> +	return !g->quirk_ep_out_aligned_size ? len : usb_ep_align(ep, len);

I’d drop the negation:

+	return g->quirk_ep_out_aligned_size ? usb_ep_align(ep, len) : len;

>  }
>  
>  /**
> -- 
> 2.9.0
>

-- 
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ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
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