linux-kernel - Re: [PATCH 01/16] ARM: scu: Provide support for parsing SCU device node to enable SCU

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Message-ID: <CAGcde9GZkaqN=7Xaenm9YsNUGoaX0vHDpRhn07heoqLMdBw=FA@mail.gmail.com>
Date:   Thu, 8 Dec 2016 20:48:08 +0530
From:   Pankaj Dubey <pankaj.dubey@...sung.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Andrew Lunn <andrew@...n.ch>, Heiko Stuebner <heiko@...ech.de>,
        geert+renesas@...der.be, Linus Walleij <linus.walleij@...aro.org>,
        Liviu Dudau <liviu.dudau@....com>,
        Michal Simek <michal.simek@...inx.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Jisheng Zhang <jszhang@...vell.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Wei Xu <xuwei5@...ilicon.com>,
        "thomas.ab@...sung.com" <thomas.ab@...sung.com>,
        "cpgs ." <cpgs@...sung.com>,
        Stephen Warren <swarren@...dotorg.org>,
        Ray Jui <rjui@...adcom.com>, Simon Horman <horms@...ge.net.au>,
        Dinh Nguyen <dinguyen@...nsource.altera.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Patrice Chotard <patrice.chotard@...com>,
        linux-kernel@...r.kernel.org, vireshk@...nel.org,
        Jun Nie <jun.nie@...aro.org>,
        Shiraz Hashim <shiraz.linux.kernel@...il.com>
Subject: Re: [PATCH 01/16] ARM: scu: Provide support for parsing SCU device
 node to enable SCU

On 18 November 2016 at 19:02, Arnd Bergmann <arnd@...db.de> wrote:
> On Friday, November 18, 2016 12:48:07 PM CET Russell King - ARM Linux wrote:
>> On Fri, Nov 18, 2016 at 01:14:35PM +0100, Arnd Bergmann wrote:
>> > @@ -41,6 +43,9 @@ void scu_enable(void __iomem *scu_base)
>> >  {
>> >       u32 scu_ctrl;
>> >
>> > +     if (scu_base)
>> > +             scu_base = scu_base_addr;
>> > +
>>
>> This looks to me like nonsense.
>>
>> >  #ifdef CONFIG_ARM_ERRATA_764369
>> >       /* Cortex-A9 only */
>> >       if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090) {
>> > @@ -85,6 +90,9 @@ int scu_power_mode(void __iomem *scu_base, unsigned int mode)
>> >       unsigned int val;
>> >       int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(smp_processor_id()), 0);
>> >
>> > +     if (scu_base)
>> > +             scu_base = scu_base_addr;
>> > +
>>
>> Ditto.
>>
>> Rather than doing this, I'd much prefer to always store the SCU base in
>> the SCU code, and remove the "void __iomem *scu_base" argment from all
>> these functions.
>
> Ok, then we just need one scu_probe_*() variant for each of the
> four methods of initializing it (iotable, of_iomap,
> ioremap(scu_a9_get_base) and hardcoded.
>
> The intention of doing the fallback for the NULL argument was
> to avoid having to add lots of new API while also allowing
> the change to be done one platform at a time.
>
> If we remove the argument from the other functions, they either
> need to get a new name, or we change them all to the new prototype
> at once. Either way works fine, do you have a preference between
> them?
>

Russell,

Any opinion on this. Are you OK, with the approach suggested by Arnd?

Thanks,
Pankaj Dubey

>         Arnd
>
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
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