linux-kernel - Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)

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Message-ID: <CAHTX3dLtFca5TaeWBX-oF6eCQyAa3h-4DKtqYEXS6QuHbDLZCg@mail.gmail.com>
Date:	Tue, 12 Feb 2013 11:03:23 +0100
From:	Michal Simek <monstr@...str.eu>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	dahinds@...rs.sourceforge.net
Subject: Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16
 with generic iowrite(read)8/16(be)

2013/2/12 Benjamin Herrenschmidt <benh@...nel.crashing.org>:
> On Mon, 2013-02-11 at 16:57 +0100, Michal Simek wrote:
>> But it reminds me that maybe the easiest solution is not to use endian
>> accessors just use two simple macros which should work on all systems.
>>
>> #define <name>_readreg(offset)          ({__raw_readl(offset); rmb(); })
>> #define <name>_writereg(offset, val)    ({wmb(); __raw_writel(val, offset); })
>>
>> which is probably the faster solution which add minimum additional code
>> to driver and can also remove endian detection code.
>
> Except that rmb & wmb might not be the right barriers for IOs ...

Arm is using __iormb in readX macros
#define __iormb()		rmb()
but it is arm specific only that's why I have added there rmb().

Thanks,
Michal




-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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