linux-kernel - Re: [PATCH v21 01/13] clocksource: arm_arch_timer: introduce two functions to get the frequency from mmio and sysreg.

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Date:   Fri, 17 Mar 2017 18:05:13 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     fu.wei@...aro.org
Cc:     rjw@...ysocki.net, lenb@...nel.org, daniel.lezcano@...aro.org,
        tglx@...utronix.de, marc.zyngier@....com,
        lorenzo.pieralisi@....com, sudeep.holla@....com,
        hanjun.guo@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linaro-acpi@...ts.linaro.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, rruigrok@...eaurora.org,
        harba@...eaurora.org, cov@...eaurora.org, timur@...eaurora.org,
        graeme.gregory@...aro.org, al.stone@...aro.org, jcm@...hat.com,
        wei@...hat.com, arnd@...db.de, catalin.marinas@....com,
        will.deacon@....com, Suravee.Suthikulpanit@....com,
        leo.duran@....com, wim@...ana.be, linux@...ck-us.net,
        linux-watchdog@...r.kernel.org, tn@...ihalf.com,
        christoffer.dall@...aro.org, julien.grall@....com
Subject: Re: [PATCH v21 01/13] clocksource: arm_arch_timer: introduce two
 functions to get the frequency from mmio and sysreg.

On Tue, Feb 07, 2017 at 02:50:03AM +0800, fu.wei@...aro.org wrote:
> +static u32 arch_timer_get_sysreg_freq(void)
> +{
> +	/*
> +	 * Try to get the frequency from the CNTFRQ of sysreg.
> +	 */
> +	return arch_timer_get_cntfrq();
> +}

We already have arch_timer_get_cntfrq(), so I don't see the point in
this wrapper.

> +static u32 arch_timer_get_mmio_freq(void __iomem *cntbase)
> +{
> +	/*
> +	 * Try to get the frequency from the CNTFRQ of timer frame registers.
> +	 * Note: please verify cntbase in caller.
> +	 */
> +	return readl_relaxed(cntbase + CNTFRQ);
> +}

Wrapping the MMIO read makes sense if we're going to do this in more
than one place, so I'm happy with this wrapper.

If you can s/arch_timer_get_mmio_freq/arch_timer_get_cntfrq/, and drop
the comments, then this looks fine to me.

Thanks,
Mark.