linux-kernel - RE: [PATCH 2/5] Clocksource: Flextimer: Use internal clocksource read API.

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Date:	Thu, 4 Sep 2014 01:49:23 +0000
From:	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	"Dongsheng.Wang@...escale.com" <Dongsheng.Wang@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/5] Clocksource: Flextimer: Use internal clocksource read
 API.

> Subject: Re: [PATCH 2/5] Clocksource: Flextimer: Use internal clocksource read
> API.
> 
> On Tue, 26 Aug 2014, Xiubo Li wrote:
> 
> > Since the Flextimer device will be implemented in BE mode on
> > LS1 SoC, and in LE mode on Vybrid, LS2 SoCs, so here we need
> > the endianness judgment before doing the mmio.
> 
> Brilliant. So for every clocksource read you take a conditional.
> 
> > @@ -238,7 +243,7 @@ static int __init ftm_clocksource_init(unsigned long
> freq)
> >  	sched_clock_register(ftm_read_sched_clock, 16, freq / (1 << priv->ps));
> >  	err = clocksource_mmio_init(priv->clksrc_base + FTM_CNT, "fsl-ftm",
> >  				    freq / (1 << priv->ps), 300, 16,
> > -				    clocksource_mmio_readl_up);
> > +				    ftm_clocksource_read_up);
> 
> What's wrong with having endianess aware clocksource_mmio functions
> and make the decision at init time?
> 

Since the FTM will be in BE mode on LS1 platform, but will be in LE mode
On LS2 platform.

And ftm_clocksource_read_up() will adapt to this different.

Thanks,

BRs
Xiubo
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