Re: [rfc/patch] libata -- port configurable delays

Jeff Garzik
2005-05-13T23:08:18Z

Alan Cox wrote:
>>>4) It may be worthwhile to rewrite the loop to check the Status register
>>>_first_, then delay.
>
>
> The 400nS delay after a command is required before status becomes valid.
> This isn't about 'incorrect' devices in the command case. It is about
> strictly correct behaviour and propogation/response times. For the cases
> its not required and you wan to keep PCI load down then checking first
> is clearly logical.

The 400nS delay isn't the one in the loop. I was referring to the other
delay.

Putting the Status register read first will also flush out any posted
writes, before delaying, and potentially exit more rapidly if the device
is immediately ready.

Jeff