Re: [PATCH] powerpc: Enable CPU_FTR_NEED_COHERENT for MPC52xx

[Grant Likely <grant.likely@secretlab.ca>]

On Tue, Mar 17, 2009 at 6:10 AM, Kumar Gala <kumar.gala@freescale.com> wrot=
e:
> On Mar 16, 2009, at 11:43 PM, Grant Likely wrote:
>> diff --git a/arch/powerpc/include/asm/cputable.h
>> b/arch/powerpc/include/asm/cput
>> index 4911104..48d7f5f 100644
>> --- a/arch/powerpc/include/asm/cputable.h
>> +++ b/arch/powerpc/include/asm/cputable.h
>> @@ -348,8 +348,15 @@ extern const char *powerpc_base_platform;
>> =A0 =A0 =A0 =A0 =A0 CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
>> #define CPU_FTRS_82XX =A0(CPU_FTR_COMMON | \
>> =A0 =A0 =A0 =A0 =A0 CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB)
>> +
>> +#if defined(CONFIG_PPC_MPC52xx)
>> +#define CPU_FTRS_G2_LE (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \
>> + =A0 =A0 =A0 =A0 =A0 CPU_FTR_USE_TB | CPU_FTR_MAYBE_CAN_NAP |
>> CPU_FTR_NEED_COHERENT)
>> +#else
>> #define CPU_FTRS_G2_LE (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \
>> =A0 =A0 =A0 =A0 =A0 CPU_FTR_USE_TB | CPU_FTR_MAYBE_CAN_NAP)
>> +#endif
>> +
>> #define CPU_FTRS_E300 =A0(CPU_FTR_MAYBE_CAN_DOZE | \
>> =A0 =A0 =A0 =A0 =A0 CPU_FTR_USE_TB | CPU_FTR_MAYBE_CAN_NAP | \
>> =A0 =A0 =A0 =A0 =A0 CPU_FTR_COMMON)
>
> Doing this via a static CPU FTR fixup isn't really the best way to handle
> it. =A0I was thinking about this the other day in my patch to actually ma=
ke
> G2/e300 cores respect _PAGE_COHERENT. =A0We really should set this via a
> platform fixup. =A0Just not sure if that's soon enough.

I agree, but as Ben pointed out last night on IRC, feature fixup
(early_init) occurs well before platform probe time.  Platform code
cannot fix it up until someone does the work of making platform probe
time earlier.  It's non-trivial.

However, I need to get a fix in for this ASAP, otherwise the 5200 will
be broken in 2.6.29.  I don't see this patch as a final solution, but
it works as a stop-gap until platform probing can be reworked.

g.

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.