[PATCH] ARM: exynos4: fix secondary CPU boot

[Marc Zyngier]

On Thu, 2011-06-02 at 17:39 +0900, Kyungmin Park wrote:
> On Thu, Jun 2, 2011 at 5:34 PM, Marc Zyngier <Marc.Zyngier at arm.com> wrote:
> > On Thu, 2011-06-02 at 16:01 +0900, Kyungmin Park wrote:
> >> 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.
> >
> > So we know there's a need beyond the wish to see the second core up and
> > running on my board.
> >
> > Now what is the proper method to detect the revision of the SOC?
> > Handling it is no problem, once we have the information. Unfortunately
> > the documentation I have is less than helpful on that subject.
> 
> It can be distinguished by chip id. but there's no code to handle this one.
> 
> 0x4320 0200 EVT0
> 0x4321 0210 EVT1
> 0x4321 0211 EVT2

Apparently, the low 8 bits can be overloaded by the efuse. Which makes
telling EVT1 from EVT2 unreliable.

But at least this is a start. I'll see if I can come up with something
minimal enough to be merged as a fix.

Thanks,

	M.
-- 
Reality is an implementation detail.