[PATCH] ARM: V7M: Set cacheid iff DminLine or IminLine is nonzero

[linux@armlinux.org.uk (Russell King - ARM Linux)]

Yea, found a copy of the ARMv7M ARM, and this seems to be sane, as the
minimum cache line size (according to CCSIDR) is 4 words, so the minimum
value in CTR for these fields should be 2 when caches are implemented.

On Thu, Jun 08, 2017 at 09:29:24AM +0100, Vladimir Murzin wrote:
> Ping!
> 
> On 26/05/17 10:52, Vladimir Murzin wrote:
> > Gentle ping...
> > 
> > On 04/05/17 09:13, Vladimir Murzin wrote:
> >> On 03/05/17 20:14, Russell King - ARM Linux wrote:
> >>> On Tue, May 02, 2017 at 09:31:24AM +0100, Vladimir Murzin wrote:
> >>>> On 26/04/17 11:04, Vladimir Murzin wrote:
> >>>>> Cache support is optional feature in M-class cores, thus DminLine or
> >>>>> IminLine of Cache Type Register is zero if caches are not implemented,
> >>>>> but we check the whole CTR which has other features encoded there.
> >>>>> Let's be more precise and check for DminLine and IminLine of CTR
> >>>>> before we set cacheid.
> >>>>>
> >>>>> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> >>>>> ---
> >>>>>  arch/arm/kernel/setup.c | 2 +-
> >>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> >>>>> index f4e5450..231a1d83 100644
> >>>>> --- a/arch/arm/kernel/setup.c
> >>>>> +++ b/arch/arm/kernel/setup.c
> >>>>> @@ -315,7 +315,7 @@ static void __init cacheid_init(void)
> >>>>>  	if (arch >= CPU_ARCH_ARMv6) {
> >>>>>  		unsigned int cachetype = read_cpuid_cachetype();
> >>>>>  
> >>>>> -		if ((arch == CPU_ARCH_ARMv7M) && !cachetype) {
> >>>>> +		if ((arch == CPU_ARCH_ARMv7M) && !(cachetype & 0xf000f)) {
> >>>>>  			cacheid = 0;
> >>>>>  		} else if ((cachetype & (7 << 29)) == 4 << 29) {
> >>>>>  			/* ARMv7 register format */
> >>>>>
> >>>>
> >>>> Ok for patch tracker?
> >>>
> >>> Not yet, I've been away and I've no time right now to evaluate this
> >>> change.  I'm hopefully going to catch up with some email in the coming
> >>> days.
> >>>
> >>
> >> Noted.
> >>
> >> Cheers
> >> Vladimir
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel at lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >>
> > 
> > 
> > _______________________________________________
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> > linux-arm-kernel at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > 
> 

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