Re: [PATCH 15/15] Do not rely on the initial state of TC/VPE bindings when doing cross VPE writes

["Kevin D. Kissell" <kevink@paralogos.com>]

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Gandham, Raghu wrote:
>   
>> -----Original Message-----
>> From: Kevin D. Kissell [mailto:kevink@paralogos.com]
>> Sent: Wednesday, July 01, 2009 9:02 PM
>> To: Gandham, Raghu
>> Cc: linux-mips@linux-mips.org; Dearman, Chris
>> Subject: Re: [PATCH 15/15] Do not rely on the initial state of TC/VPE
>> bindings when doing cross VPE writes
>>
>> Note that, regardless of the reset state, smtc_configure_tlb() should
>> have at least temporarily bound TC 1 to VPE1, which may be why this
>> never seemed to be a problem on the 34K.  If one wants to support
>> designs with more than 2 VPEs, then this is probably one of the things
>> that needs to be fixed.  That having been said, rather than adding a
>> usually-redundant write_vpe_c0_vpeconf0() in that clause, wouldn't it
>>     
> be
>   
>> cleaner to just move the MVP setting from the top of the loop to the
>> point in the loop just after the TCs have been bound to the VPE in
>> question, i.e.,
>>
>>  454                 if (slop) {
>>  455                         if (tc != 0) {
>>  456                                 smtc_tc_setup(vpe,tc, cpu);
>>  457                                 cpu++;
>>  458                         }
>>  459                         printk(" %d", tc);
>>  460                         tc++;
>>  461                         slop--;
>>  462                 }
>>
>>                         write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() |
>> VPECONF0_MVP);
>>
>>  463                 if (vpe != 0) {
>>  464                         /*
>>  465                          * Clear any stale software interrupts
>>     
> from
>   
>> VPE's Cause
>>  466                          */
>>
>> This should definitely be OK for a 34K, because it's being executed by
>> TC0 in VPE0 and the reset state of VPE0 has MVP set.  If it weren't,
>> smtc_configure_tlb() would have failed.
>>
>>           Regards,
>>
>>           Kevin K.
>>     
>
>
> I will resend this patch with your suggestion.
>
> Thanks,
> Raghu
>   
Just make sure it works, first!  ;o)  I'm thousands of miles away from 
my build/test systems.

          Regards,

          Kevn K.

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