linux-kernel - Re: [PATCH 3/3] ARM: errata 430973: move !ARCH

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Date:	Mon, 27 Jul 2015 03:14:47 +0200
From:	Sebastian Reichel <sre@...nel.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Tony Lindgren <tony@...mide.com>,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] ARM: errata 430973: move !ARCH_MULTIPLATFORM to
 Kconfig

Hi,

On Sun, Jul 26, 2015 at 11:51:45PM +0100, Russell King - ARM Linux wrote:
> On Fri, Jul 24, 2015 at 02:16:06AM +0200, Sebastian Reichel wrote:
> > On Thu, Jul 23, 2015 at 01:35:53PM +0100, Russell King - ARM Linux wrote:
> > > On Thu, Jul 23, 2015 at 02:48:03AM +0200, Sebastian Reichel wrote:
> > > > Having the !ARCH_MULTIPLATFORM dependency in the Kconfig file results
> > > > in one option less to think about when configuring the kernel.
> > > 
> > > > -#if defined(CONFIG_ARM_ERRATA_430973) && !defined(CONFIG_ARCH_MULTIPLATFORM)
> > > > +#ifdef CONFIG_ARM_ERRATA_430973
> > > >  	teq	r3, #0x00100000			@ only present in r1p*
> > > >  	mrceq	p15, 0, r0, c1, c0, 1		@ read aux control register
> > > >  	orreq	r0, r0, #(1 << 6)		@ set IBE to 1
> > > 
> > > NAK.  Please read the mailing list history, I'm not repeating myself
> > > again on this.  Thanks.
> > 
> > It's a bit hard to search the mailing list history without a bit
> > more information.
> 
> You were Cc'd on the previous round of review...

But that discussion was about removing the check alltogether iirc.
This patch does not remove the !ARCH_MULTIPLATFORM check. It just
*moves* it from the sourcecode to the errata's Kconfig entry.

The intention was to hide the Kconfig option on multiplatform
kernels, since it's completely useless there after the N900
boardcode has been changed (PATCH 1/3).

> > I guess you prefer to just add the !ARCH_MULTIPLATFORM dependency to
> > the Kconfig entry without removing the additional check in the code?
> 
> I was referring to the above change.
>
> However, having discussed with Will Deacon and checked the manuals, I
> think the change is okay after all: the auxillary control register is
> banked on secure parts, and the bit we'll be trying to change will be
> read-only in non-secure mode - and importantly won't fault.
>
> So, the change is fine, thanks.

I think you missed the part adding the !ARCH_MULTIPLATFORM
dependency in Kconfig for ARM_ERRATA_430973. I only removed
the check in the sourcecode, since it is no longer required
with the dependency being in Kconfig.

So I guess there are 3 options now:

 1. Add !ARCH_MULTIPLATFORM dependency to Kconfig,
    keep extra check in the sourcecode
 2. Add !ARCH_MULTIPLATFORM dependency to Kconfig,
    remove extra check in the sourcecode
 3. Remove !ARCH_MULTIPLATFORM dependency alltogether

I will send an appropriate patch, if you tell me your preferred
option.

-- Sebastian

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