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

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Date:	Tue, 2 Aug 2016 16:05:39 +0100
From:	Felipe Ferreri Tonello <eu@...ipetonello.com>
To:	Michal Nazarewicz <mina86@...a86.com>, linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
	Baolin Wang <baolin.wang@...aro.org>
Subject: Re: [PATCH 1/9] usb: gadget: fix usb_ep_align_maybe endianness and
 new usb_ep_align

Hi Michal,

On 27/07/16 20:37, Michal Nazarewicz wrote:
> 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;

Agreed.

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

-- 
Felipe

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