On Nov 30, 2010, at 7:50 PM, Scott Wood wrote:
> On Tue, 30 Nov 2010 18:36:25 -0600
> Timur Tabi <ti...@freescale.com> wrote:
>
>> @@ -244,8 +266,15 @@ void flash_write64(u64 value, void *addr)
>>
>> /* There is no __raw_writeq(), so do the write manually */
>> *(volatile u64 *)addr = value;
>> - if (sw)
>> + if (sw) {
>> + /*
>> + * To ensure the post-write is completed to eLBC, software must
>> + * perform a dummy read from one valid address from eLBC space
>> + * before changing the eLBC_DIU from NOR mode to DIU mode.
>> + */
>> + __raw_readb(addr);
>> set_mux_to_diu();
>> + }
>
> Careful with the barriers.
>
> You've got a raw readback, which means it's not going to wait for
> completion with the twi/isync hack.
>
> Ordinarily that would be OK, since you only need ordering between the
> readb and the first access in set_mux_to_diu(). Unfortunately, that
> first access is an 8-bit access, which for some strange reason does
> sync differently than 16/32-bit accesses. The latter do sync+write,
> but 8-bit does write+eieio. So there's no barrier between the read
> and the write.
Any reason not to use in_8 here?
- k
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