linux-kernel - Re: [PATCH V2 05/19] bus: omap_l3_noc: switch over to relaxed variants of readl/writel

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Date:	Mon, 21 Apr 2014 08:16:28 -0500
From:	Nishanth Menon <nm@...com>
To:	<balbi@...com>, Santosh Shilimkar <santosh.shilimkar@...com>
CC:	Tony Lindgren <tony@...mide.com>, Sricharan R <r.sricharan@...com>,
	Sekhar Nori <nsekhar@...com>, Rajendra Nayak <rnayak@...com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 05/19] bus: omap_l3_noc: switch over to relaxed variants
 of readl/writel

On 04/17/2014 05:03 PM, Felipe Balbi wrote:
> On Thu, Apr 17, 2014 at 05:56:15PM -0400, Santosh Shilimkar wrote:
>> On Thursday 17 April 2014 05:52 PM, Felipe Balbi wrote:
>>> Hi,
>>>
>>> On Thu, Apr 17, 2014 at 03:49:21PM -0500, Nishanth Menon wrote:
>>>> Currently we use __raw_readl and writel in this driver, however, there
>>>
>>> __raw_* and *_relaxed variants are the same, just have a look <asm/io.h>
>>>
>> Except the relaxed version can take care of endian conversion if
>> needed. :-)
> 
> right, but according to commit log, this commit is more concerned about
> the memory barriers which writel()/readl() add, not endianness. Just a
> matter of fixing up commit log.
> 

yep, this patch does replace writel with writel_relaxed there is no
strong need for barriers in the operations that we perform here.

I agree that the commit message should probably be a little more
detailed at this point.


How about:
Currently we use __raw_readl and writel in this driver. Considering
there is no specific need for a memory barrier, replacing writel with
endian-neutral writel_relaxed and replacing __raw_readls with the
corresponding endian-neutral readl_relaxed allows us to have a
standard set of register operations for the driver.

While at it, simplify address computation using variables for register.


-- 
Regards,
Nishanth Menon
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