[PATCH 3/3] ARM: Work around faulty ISAR0 register in some Krait CPUs

Will Deacon will.deacon at arm.com
Mon Mar 18 14:19:08 EDT 2013


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 at arm.com>
> >> Cc: Stepan Moskovchenko <stepanm at codeaurora.org>
> >> Signed-off-by: Stephen Boyd <sboyd at 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



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