linux-kernel - Re: [PATCH v4 1/6] mtd: nand: vf610_nfc: Freescale NFC for VF610, MPC5125 and others

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Date:	Tue, 09 Jun 2015 22:31:07 +0200
From:	Stefan Agner <stefan@...er.ch>
To:	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
Cc:	dwmw2@...radead.org, computersforpeace@...il.com,
	mark.rutland@....com, boris.brezillon@...e-electrons.com,
	aaron@...tycactus.com, marb@...at.de, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, robh+dt@...nel.org,
	linux-mtd@...ts.infradead.org, kernel@...gutronix.de,
	galak@...eaurora.org, shawn.guo@...aro.org,
	linux-arm-kernel@...ts.infradead.org, bpringlemeir@...ps.com
Subject: Re: [PATCH v4 1/6] mtd: nand: vf610_nfc: Freescale NFC for VF610,
 MPC5125 and others

On 2015-06-09 22:07, Sebastian Andrzej Siewior wrote:
> On 2015-06-03 17:05:16 [+0200], Stefan Agner wrote:
>> As Boris guessed correctly, the reason I used the raw variant was due to
>> performance improvements due to the barrier. However, I will use
> 
> yeah, do you have any numbers by chance?

Not current ones for Linux. I added this in the U-Boot variant of the
driver.
 
>> {read|write}l_relaxed instead, which should offer endian abstraction
>> while not having the performance penalty due to extensive barriers...
> 
> well, even those
> |$ git grep readl_relaxed arch/powerpc/
> |arch/powerpc/include/asm/io.h:#define readl_relaxed(addr) readl(addr)
> 
> have the endian swap. So an abstraction like you provided earlier
> would be nice :)

What do you mean by that?

Btw, I sent v5 of the patchset which use the relaxed variants. As
expected, performance did not suffer by that change on ARM.

--
Stefan
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