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

To: "'Marc Kleine-Budde'" <mkl@pengutronix.de>, "'Alexander Shishkin'" <alexander.shishkin@linux.intel.com>
Subject: RE: [PATCH v2 1/2] usb: chipidea: big-endian support
From: "Svetoslav Neykov" <svetoslav@neykov.name>
Date: Fri, 10 May 2013 00:22:41 +0300
Cc: "'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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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.

Regards,
Svetoslav.



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