linux-kernel - Re: [PATCH V5] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available

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Date:   Tue, 28 May 2019 18:05:09 +0200
From:   Simon Horman <horms@...ge.net.au>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Oleksandr Tyshchenko <olekstysh@...il.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Julien Grall <julien.grall@....com>,
        Magnus Damm <magnus.damm@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
Subject: Re: [PATCH V5] ARM: mach-shmobile: Don't init CNTVOFF/counter if
 PSCI is available

On Tue, May 28, 2019 at 10:27:56AM +0200, Geert Uytterhoeven wrote:
> Hi Oleksandr,
> 
> On Fri, May 17, 2019 at 11:58 AM Oleksandr Tyshchenko
> <olekstysh@...il.com> wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> >
> > If PSCI is available then most likely we are running on PSCI-enabled
> > U-Boot which, we assume, has already taken care of resetting CNTVOFF
> > and updating counter module before switching to non-secure mode
> > and we don't need to.
> >
> > As the psci_smp_available() helper always returns false if CONFIG_SMP
> > is disabled, it can't be used safely as an indicator of PSCI usage.
> > For that reason, we check for the mandatory PSCI operation to be
> > available.
> >
> > Please note, an extra check to prevent secure_cntvoff_init() from
> > being called for secondary CPUs in headsmp-apmu.S is not needed,
> > as SMP code for APMU based system is not executed if PSCI is in use.
> >
> > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> 
> >    Changes in v5:
> >       - Check for psci_ops.cpu_on if CONFIG_ARM_PSCI_FW is defined
> 
> Thanks for the update!
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> 
> Two cosmetic comments below. I'll leave it to Simon to ignore them for
> applying ;-)

Oleksandr, could I trouble you to respin with the
changes suggested by Geert?

> 
> > @@ -62,6 +63,21 @@ void __init rcar_gen2_timer_init(void)
> >  {
> >         void __iomem *base;
> >         u32 freq;
> > +       bool need_update = true;
> 
> Some people like reverse Xmas tree declaration order...
> 
> > +
> > +       /*
> > +        * If PSCI is available then most likely we are running on PSCI-enabled
> > +        * U-Boot which, we assume, has already taken care of resetting CNTVOFF
> > +        * and updating counter module before switching to non-secure mode
> > +        * and we don't need to.
> > +        */
> > +#if defined(CONFIG_ARM_PSCI_FW)
> 
> #ifdef CONFIG_ARM_PSCI_FW ?
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>