Re: [PATCH] 2.5.15 IDE 61

[Martin Dalecki]

Uz.ytkownik Neil Conway napisa?:
> Martin Dalecki wrote:
> 
>>There is no problem to go in paralell on different channels for
>>requests. The serialization has only to be done
>>for the drive setup.
> 
> 
> I agree for general chipsets, but my whole point was with regard to
> buggy chipsets which need to be serialized on both channels.
> 
> If you're saying that even these broken chipsets are OK with having
> transfers on one channel while setting up transfers on another channel,
> then perhaps you are right but that's not what I believed to be the case
> (can't find info to tell me either way right now).
> 
> But if that really were the case, then how could the (e.g.) cmd640
> problem ever have been manifested?  A spinlock is ALWAYS held while
> ide_do_request is executing.  Even if it weren't, only an SMP machine
> could be trying to program both channels simultaneously because
> interrupts are disabled too.

Well in the next patch round the hwgroup will be replaced with
a spin lock, which is supposed to be shared between channels which need
forced access serialization between them. Please look
at patches 62a and 63 :-).