Re: [PATCH] ARM: mach-shmobile: Don't configure ARCH timer if PSCI is enabled

[Oleksandr]

On 18.04.19 12:32, Julien Grall wrote:
> Hi,

Hi Julien


<snip>

> > diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c 
> > b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > index eea60b2..bac4490 100644
> > --- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > +++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > @@ -32,7 +32,7 @@ static const struct of_device_id cpg_matches[] 
> > __initconst = {
> > ÂÂÂÂÂ { /* sentinel */ }
> > Â };
> > Â -static unsigned int __init get_extal_freq(void)
> > +static unsigned int __init __maybe_unused get_extal_freq(void)
> > Â {
> > ÂÂÂÂÂ const struct of_device_id *match;
> > ÂÂÂÂÂ struct device_node *cpg, *extal;
> > @@ -60,6 +60,12 @@ static unsigned int __init get_extal_freq(void)
> > Â Â void __init rcar_gen2_timer_init(void)
> > Â {
> > +/*
> > + * If CONFIG_PSCI is enabled then most likely we are running on 
> > PSCI-enabled
> > + * U-Boot which, we assume, has already taken care of configuring 
> > ARCH timer
> > + * stuff before switching to non-secure mode.
> > + */
>
> I disagree with that statement. CONFIG_ARM_PSCI may be selected in 
> your .config for multiple reasons:
> ÂÂÂÂ - CONFIG_XEN will selected it
> ÂÂÂÂ - you build a .config targeting multiple platforms
>
> Yet you may still want to boot the kernel on older U-boot. Such change 
> would make it impossible.
>
> If there are code that should not be called when PSCI is used, then 
> you need to make sure the function is not called at runtime.

I got your point.


As I answered in a previous email:

> But "#if !defined(CONFIG_ARM_PSCI)" wraps secure_cntvoff_init() call as
> well, which resets CNTVOFF,

> and this is something I tried to avoid the first from being executed on
> a CPU, which is in SVC mode (when running on top of Xen).

What would be a proper way to avoid calling secure_cntvoff_init() at 
runtime?

Check that we are already in non-secure mode and/or cntvoff is already 0?


> Cheers,
--
Regards,

Oleksandr Tyshchenko