[PATCH] ARM: exynos4: fix secondary CPU boot

[Kyungmin Park]

On Fri, May 27, 2011 at 12:11 AM, Marc Zyngier <Marc.Zyngier at arm.com> wrote:
> On Wed, 2011-05-25 at 12:06 -0700, Kukjin Kim wrote:
>> On 05/25/11 11:04, Marc Zyngier wrote:
>> > On Wed, 2011-05-25 at 10:28 -0700, Kukjin Kim wrote:
>> >> On 05/20/11 06:46, Marc Zyngier wrote:
>>
>> (snip)
>>
>> > So that address has changed between two SoC revisions? That's
>> > unfortunate, to say the least. I'm most probably using an early revision
>> > of the hardware (EVT0?), as it doesn't even support MCT.
>> >
>> I'm afraid :( and I agree secondary CPU should work on all of
>> Exynos4210. But I'm still think about the method...
>>
>> > What about the following patch?
>> >
>> Uhm...this is really hack but I'd like to use another normal way...?
>
> Oh, no question about the hack status. The trouble is, unless there is a
> sure way to tell which SoC revision we're running on, there's little
> else we can do than poke both locations and pray.
>
> Is there such a way to identify the SoC revision?

It's also required for OneNAND. as you know C210 EVT0 OneNAND DMA has
bug and need to workaround.

platform codes should provide the these function. please see the OMAP
codes. how to handle it.

Thank you,
Kyungmin Park
>
>> >> From c27e75b86e1ee181987a9364286a888421e76205 Mon Sep 17 00:00:00 2001
>> > From: Marc Zyngier<marc.zyngier at arm.com>
>> > Date: Fri, 20 May 2011 14:38:25 +0100
>> > Subject: [PATCH] ARM: exynos4: fix secondary CPU boot on early SoC revisions
>> >
>> > It appears that the system-wide flags register that used to be at
>> > 0x02025000 on the first revision of Exynos4 has moved to 0x02020000.
>> >
>> > The kernel has been updated accordingly, but this unfortunately leaves
>> > early boards without SMP support (the secondary CPU spins endlessly
>> > in BL0 waiting for an address to be written at that memory location).
>> >
>> > Try to solve the problem by poking both locations. This should be
>> > safe as this is done early enough in the kernel boot process, and nobody
>> > should be using the SRAM yet.
>> >
>> > Tested on a vintage SMDK-v310.
>>
>> vintage ;)
>
> Well, I thought I was the uber-cool guy in the office because of that
> shiny blue board on my desk, only to discover that it's sooo last
> year... ;-)
>
>> >
>> > Cc: Kukjin Kim<kgene.kim at samsung.com>
>> > Signed-off-by: Marc Zyngier<marc.zyngier at arm.com>
>> > ---
>> >   arch/arm/mach-exynos4/include/mach/map.h |    1 +
>> >   arch/arm/mach-exynos4/platsmp.c          |   14 ++++++++++++++
>> >   2 files changed, 15 insertions(+), 0 deletions(-)
>> >
>> > diff --git a/arch/arm/mach-exynos4/include/mach/map.h b/arch/arm/mach-exynos4/include/mach/map.h
>> > index 0009e77..781e149 100644
>> > --- a/arch/arm/mach-exynos4/include/mach/map.h
>> > +++ b/arch/arm/mach-exynos4/include/mach/map.h
>> > @@ -24,6 +24,7 @@
>> >   #include<plat/map-s5p.h>
>> >
>> >   #define EXYNOS4_PA_SYSRAM         0x02020000
>> > +#define EXYNOS4_PA_SYSRAM_EVT0             0x02025000
>> >
>> >   #define EXYNOS4_PA_FIMC0          0x11800000
>> >   #define EXYNOS4_PA_FIMC1          0x11810000
>> > diff --git a/arch/arm/mach-exynos4/platsmp.c b/arch/arm/mach-exynos4/platsmp.c
>> > index c5e65a0..f261c34 100644
>> > --- a/arch/arm/mach-exynos4/platsmp.c
>> > +++ b/arch/arm/mach-exynos4/platsmp.c
>> > @@ -155,6 +155,7 @@ void __init smp_init_cpus(void)
>> >   void __init platform_smp_prepare_cpus(unsigned int max_cpus)
>> >   {
>> >     int i;
>> > +   void __iomem *sysram_evt0;
>> >
>> >     /*
>> >      * Initialise the present map, which describes the set of CPUs
>> > @@ -172,4 +173,17 @@ void __init platform_smp_prepare_cpus(unsigned int max_cpus)
>> >      * secondary CPU branches to this address.
>> >      */
>> >     __raw_writel(BSYM(virt_to_phys(exynos4_secondary_startup)), S5P_VA_SYSRAM);
>> > +
>> > +   /*
>> > +    * EVT0 has the system-wide flags register at a different address.
>> > +    * Poke it as well, in case we're running on an old SoC revision.
>> > +    */
>> > +   sysram_evt0 = ioremap(EXYNOS4_PA_SYSRAM_EVT0, SZ_4K);
>>
>> Hmm...first of all, need to check whether can ioremap the area on newer
>> one but I'm out off office now so will check it after backing.
>
> The only documentation I have access to refers to the iRAM (SRAM) being
> mapped between 0x02020000 and 0x02040000. Unless the HW guys have gone
> completely wild and changed this range as well, I think we're pretty
> safe.
>
>> > +   if (!sysram_evt0) {
>> > +           pr_err("Unable to remap EXYNOS4_PA_SYSRAM_EVT0\n");
>>
>> Do we really need 'pr_err' here?...
>
> No. Anything will do. Though not being able to ioremap() that region may
> indicate further trouble down the road.
>
>> > +           return;
>> > +   }
>> > +
>> > +   __raw_writel(BSYM(virt_to_phys(exynos4_secondary_startup)), sysram_evt0);
>> > +   iounmap(sysram_evt0);
>> >   }
>>
>
> Cheers,
>
>        M.
> --
> Reality is an implementation detail.
>
>
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