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Re: [PATCH v2 1/2] usb: chipidea: big-endian support

To: Svetoslav Neykov <svetoslav@neykov.name>
Subject: Re: [PATCH v2 1/2] usb: chipidea: big-endian support
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Wed, 15 May 2013 16:29:46 +0200
Cc: 'Alexander Shishkin' <alexander.shishkin@linux.intel.com>, 'Ralf Baechle' <ralf@linux-mips.org>, 'Greg Kroah-Hartman' <gregkh@linuxfoundation.org>, 'Gabor Juhos' <juhosg@openwrt.org>, 'John Crispin' <blogic@openwrt.org>, 'Alan Stern' <stern@rowland.harvard.edu>, "'Luis R. Rodriguez'" <mcgrof@qca.qualcomm.com>, linux-mips@linux-mips.org, linux-usb@vger.kernel.org
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On 05/09/2013 11:22 PM, Svetoslav Neykov wrote:
> Hi Marc,
> 
> Marc Kleine-Budde [mailto:mkl@pengutronix.de] (On Thursday, March 28, 2013
> 4:16 PM)
>> On 03/28/2013 10:28 AM, Alexander Shishkin wrote:
>>> Svetoslav Neykov <svetoslav@neykov.name> writes:
>>>
>>>> Convert between big-endian and little-endian format when accessing
>>>> the usb controller structures which are little-endian by
>>>> specification. Fix cases where the little-endian memory layout is
>>>> taken for granted. The patch doesn't have any effect on the already
>>>> supported little-endian architectures.
>>
>> Has anyone tested how the cpu_to_le32 and vice versa effects the
>> load/store operations? Does the compiler generate full 32 bit accesses
>> on mips (and big endian arm) or is a byte-shift-or pattern used?
> 
> Better late than never... I have checked your question, the value is loaded
> in a register and then swapped, so the read is performed only once.

Thanks for checking this.

Marc

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