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From: Will Deacon <will.deacon@arm.com>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
	Stepan Moskovchenko <stepanm@codeaurora.org>
Subject: Re: [PATCH 3/3] ARM: Work around faulty ISAR0 register in some Krait CPUs
Date: Mon, 18 Mar 2013 18:19:08 +0000	[thread overview]
Message-ID: <20130318181908.GC31193@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <514748F5.70504@codeaurora.org>

On Mon, Mar 18, 2013 at 05:03:49PM +0000, Stephen Boyd wrote:
> On 03/17/13 07:28, Will Deacon wrote:
> > On Wed, Mar 13, 2013 at 01:32:01AM +0000, Stephen Boyd wrote:
> >> Some early versions of the Krait CPU design incorrectly indicate
> >> that they only support the UDIV and SDIV instructions in Thumb
> >> mode when they actually support them in ARM and Thumb mode. It
> >> seems that these CPUs follow the DDI0406B ARM ARM which has two
> >> possible values for the divide instructions field, instead of the
> >> DDI0406C document which has three possible values.
> >>
> >> Work around this problem by checking the MIDR against Krait CPUs
> >> with this faulty ISAR0 register and force the detection code
> >> to indicate support in both modes.
> >>
> >> Cc: Will Deacon <will.deacon@arm.com>
> >> Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
> >> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> >> ---
> >>  arch/arm/kernel/setup.c | 8 ++++++++
> >>  1 file changed, 8 insertions(+)
> > After all this, you might as well just pass the relevant HWCAPs for your
> > krait entry in proc-v7.S rather than have an exception in the CPU-agnostic
> > code.
> 
> Ok. Care to ack the previous patch I sent then?

Gah, I can't find the original one. If you resend the series with the
changes I suggested in the other mail, I'll add the necessary acks there.

Will

      reply	other threads:[~2013-03-18 18:19 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-13  1:31 [PATCH 0/3] Detect UDIV/SDIV support from ISAR0 Stephen Boyd
2013-03-13  1:31 ` [PATCH 1/3] ARM: Clear IDIVT hwcap if CONFIG_ARM_THUMB=n Stephen Boyd
2013-03-17 14:29   ` Will Deacon
2013-03-13  1:32 ` [PATCH 2/3] ARM: Detect support for SDIV/UDIV from ISAR0 register Stephen Boyd
2013-03-17 14:36   ` Will Deacon
2013-03-18 17:13     ` Stephen Boyd
2013-03-13  1:32 ` [PATCH 3/3] ARM: Work around faulty ISAR0 register in some Krait CPUs Stephen Boyd
2013-03-17 14:28   ` Will Deacon
2013-03-18 17:03     ` Stephen Boyd
2013-03-18 18:19       ` Will Deacon [this message]

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