Re: [PATCH #upstream-fixes] libata: implement and use HORKAGE_NOSETXFER

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Alan Cox wrote:

>>That isn't possible because the host machine state is unknown after a
>>timeout.  The problem is not confined to TF based controllers and even
>>on TF based controllers, it's far too dangerous to continue as nothing
>>happened.  That can easily lead to complete system lock up on quite a
>>few controllers due to fragile TF emulation layer.

> It works fine on old style taskfile controllers, and the old IDE layer
> has done it for years

>>The drive is full SATA.  SETXFER doesn't mean anything to it.  Let's
>>just skip it.

> What if there is a bridge, what if the controller needs SETXFER for
> internal use (HPT PATA with on card SATA bridges) ?

    Do you mean HPT36x/37x here? If so, what internal use the controller has 
for this command?

> I have a feeling this is one case where there isn't a generic solution
> for all devices

> For PATA we need SETXFER to be issued
> For SATA we can maybe avoid it sometimes but its getting into deeply
> undefined territory and will break the early HPT at least.

    Hm...

> Alan

MBR, Sergei