Andrew Hall wrote:
>>> For some reason, mwdma doesn't work in libata now.  I'm not sure why
>>> tho.  Alan, can you enlighten us?
>> No idea at all. All my hardware is still happy. 2.6.20 is an "old"
>> kernel
>> however so it does predate the fixes you did for ata_piix mode setup ?
> 
> Old - yes, but more stable in all other respects it seems to the .21 series.
> Are these patches available for me to try on .20 or are there dependencies
> on 21? 
> 

I suppose you were using ata_piix too in older kernel, right?  Can you
post the boot dmesg of 2.6.19?  We used to ignore mwdma mode before and
enabled it at some point after that.  That may be the cause here.

Also, please try the attached patch on top of 2.6.20.

-- 
tejun