linux-kernel - RE: [PATCH v2] clocksource: Add BE APIs support for clocksource counter reading.

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Message-ID: <alpine.DEB.2.02.1409300027150.22082@ionos.tec.linutronix.de>
Date:	Tue, 30 Sep 2014 00:38:59 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>
cc:	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	"john.stultz@...aro.org" <john.stultz@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2] clocksource: Add BE APIs support for clocksource
 counter reading.

On Sun, 28 Sep 2014, Li.Xiubo@...escale.com wrote:
> > Subject: Re: [PATCH v2] clocksource: Add BE APIs support for clocksource
> > counter reading.
> > 
> > On Fri, 26 Sep 2014, Xiubo Li wrote:
> > > For now I just added  _be() support using ioread{16,32}be.
> > > And i have a check of the clocksource drivers, didn't find anyone
> > > using LE mode on one BE SoC, so _le() APIs is not needed.
> > 
> > Nonsense. The existing clocksource_mmio accessor function are
> > providing LE access independent of the CPU endianess. So we don't need
> > an _le() API simply because we have it already.
> > 
> > >  cycle_t clocksource_mmio_readl_up(struct clocksource *c)
> > >  {
> > > -	return (cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
> > > +	return (cycle_t)ioread32(to_mmio_clksrc(c)->reg);
> > 
> > And how exactly is this change related to adding BE support?
> > 
> 
> Actually not very much, since the _be() APIs are using ioread{16,32}be(),
> so I think using ioread{16,32}() will be less odd to having two different
> accessors here.
> 
> Wouldn't this be more unified somehow ?  

Changing existing code wants to be a separate patch with a proper
changelog and a proper argument WHY it needs to be changed in the
first place.

So please provide that separate patch first with a VERY REASONABLE
explanation in the changelog WHY the existing readl_relaxed() should
be replaced by ioread32().

Thanks,

	tglx
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