RE: [PATCH 3/5] ARM: l2x0: Errata fix for flush by Way operation can cause data corruption

Santosh Shilimkar
2011-02-14T05:08:38Z

> -----Original Message-----
> From: Andrei Warkentin [mailto:andreiw@motorola.com]
> Sent: Sunday, February 13, 2011 4:48 AM
> To: Santosh Shilimkar
> Cc: linux-omap@vger.kernel.org; Kevin Hilman; tony@atomide.com;
> linux-arm-kernel@lists.infradead.org; Catalin Marinas
> Subject: Re: [PATCH 3/5] ARM: l2x0: Errata fix for flush by Way
> operation can cause data corruption
>
> On Sat, Feb 12, 2011 at 11:59 AM, Santosh Shilimkar
> <santosh.shilimkar@ti.com> wrote:
> >> -----Original Message-----
> >> From: Andrei Warkentin [mailto:andreiw@motorola.com]
> >> Sent: Saturday, February 12, 2011 11:20 PM
> >> To: Santosh Shilimkar
> >> Cc: linux-omap@vger.kernel.org; khilman@ti.com; tony@atomide.com;
> >> linux-arm-kernel@lists.infradead.org; Catalin Marinas
> >> Subject: Re: [PATCH 3/5] ARM: l2x0: Errata fix for flush by Way
> >> operation can cause data corruption
> >>
> > [....]
> >
> >>
> >> Can these PL310 errata fixes be made more generic? PL310 is
> present
> >> in
> >> non-OMAP platforms too, which lack the TI hypervisor. And these
> >> platforms might have the same PL310 rev, and suffer the same
> >> glitches.
> >> While ideally there is some kind of hypervisor_ops to modify the
> >> protected register, at the very least there should be the generic
> >> debug_write handling the  "I  can write all PL310 regs" case. If
> >> you're interested I have a patch someplace that tried to do this,
> >> hopefully I can still find it.
> >
> > They are kind of generic. If you look at it, the only change
> > Which is arch specific is the implementation of "debug_writel"
> function.
> > Today this code is not in generic PL310 code, but
> > OMAP specific.
> >
> > May be we can make this as exported function pointer, which
> > arch's can populate.
> >
> > Will that work for you ?
> >
> > Regards,
> > Santosh
> >
>
> Ie something like the following.... what do you think???
>
> #define L2X0_DCR (0xF40)
>
> static void debug_writel(unsigned long val)
> {
> #ifdef CONFIG_ARCH_OMAP4
> omap_smc1(0x100, val);
> #else
> writel_relaxed(val, l2x0_base + L2X0_DCR);
> #endif
> }
> ...
I understood that from first comment. But I am not in favor
of polluting common ARM files with SOC specific #ifdeffery.
We have gone over this when first errata support
was added for PL310

I have a better way to handle this scenario.
Expect an updated patch for this.

Regards,
Santosh
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