[PATCH v2] ARM: Exynos4: read initial state of power domain from hw registers

[Marek Szyprowski]

Hello,

On Thursday, May 10, 2012 11:09 AM Kukjin Kim wrote:

> Marek Szyprowski wrote:
> >
> > Some bootloaders disable unused power domains, so kernel code should
> > read the actual state from the hardware registers instead of assuming
> > that their initial state is 'on'.
> >
> > Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> > Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> > ---
> >  arch/arm/mach-exynos/pm_domains.c |    9 ++++++---
> >  1 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm/mach-exynos/pm_domains.c b/arch/arm/mach-
> > exynos/pm_domains.c
> > index 13b3068..26fc47d 100644
> > --- a/arch/arm/mach-exynos/pm_domains.c
> > +++ b/arch/arm/mach-exynos/pm_domains.c
> > @@ -151,9 +151,12 @@ static __init int exynos4_pm_init_power_domain(void)
> >  	if (of_have_populated_dt())
> >  		return exynos_pm_dt_parse_domains();
> >
> > -	for (idx = 0; idx < ARRAY_SIZE(exynos4_pm_domains); idx++)
> > -		pm_genpd_init(&exynos4_pm_domains[idx]->pd, NULL,
> > -				exynos4_pm_domains[idx]->is_off);
> > +	for (idx = 0; idx < ARRAY_SIZE(exynos4_pm_domains); idx++) {
> > +		struct exynos_pm_domain *pd = exynos4_pm_domains[idx];
> > +		int on = __raw_readl(pd->base + 0x4) & S5P_INT_LOCAL_PWR_EN;
> > +
> > +		pm_genpd_init(&pd->pd, NULL, !on);
> > +	}
> >
> >  #ifdef CONFIG_S5P_DEV_FIMD0
> >  	exynos_pm_add_dev_to_genpd(&s5p_device_fimd0, &exynos4_pd_lcd0);
> > --
> > 1.7.1.569.g6f426
> 
> As you said, if bootloader changed some hardware setting which is not
> expected value in kernel, it should be notified to kernel. But for
> pm_domaine->is_off, it should be via DT on EXYNOS now. As you know, the
> functionality has been already implemented on dt.

I really doubt that we need such complex interface to pass the information 
which the driver can simply read from the register...

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center