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:   Mon, 20 Mar 2017 17:43:29 +0800
From:   Fu Wei <fu.wei@...aro.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        rruigrok@...eaurora.org, "Abdulhamid, Harb" <harba@...eaurora.org>,
        Christopher Covington <cov@...eaurora.org>,
        Timur Tabi <timur@...eaurora.org>,
        G Gregory <graeme.gregory@...aro.org>,
        Al Stone <al.stone@...aro.org>, Jon Masters <jcm@...hat.com>,
        Wei Huang <wei@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Leo Duran <leo.duran@....com>,
        Wim Van Sebroeck <wim@...ana.be>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org, Tomasz Nowicki <tn@...ihalf.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Julien Grall <julien.grall@....com>
Subject: Re: [PATCH v21 01/13] clocksource: arm_arch_timer: introduce two
 functions to get the frequency from mmio and sysreg.

Hi Mark,

On 20 March 2017 at 15:36, Fu Wei <fu.wei@...aro.org> wrote:
> Hi Mark,
>
> On 18 March 2017 at 02:05, Mark Rutland <mark.rutland@....com> wrote:
>> 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
>
> sorry, May I guess that is
> "s/arch_timer_get_mmio_freq/arch_timer_get_mmio_cntfrq/"
> or
> "s/arch_timer_get_mmio_freq/arch_timer_mem_get_cntfrq/"
>
> which one do you prefer? :-)

keeping using arch_timer_get_cntfrq();  for per-CPU arch timer, then

+static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase)
+{
+       return readl_relaxed(cntbase + CNTFRQ);
+}
+

Is that OK for you?

>
>> the comments, then this looks fine to me.
>>
>> Thanks,
>> Mark.
>
>
>
> --
> Best regards,
>
> Fu Wei
> Software Engineer
> Red Hat



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat