Re: [PATCH 2/4] libata: Drain data on errors

[Mark Lord <liml@rtr.ca>]

Alan Cox wrote:
> From: Alan Cox <alan@redhat.com>
> 
> If the device is signalling that there is data to drain after an error we
> should read the bytes out and throw them away. Without this some devices
> and controllers get wedged and don't recover.
> 
> Based on earlier work by Mark Lord
> 
> Signed-off-by: Alan Cox <alan@redhat.com>
..
> +	/* Drain up to 64K of data before we give up this recovery method */
> +	for (count = 0; (ap->ops->sff_check_status(ap) & ATA_DRQ)
> +							&& count < 65536;)
> +		ioread8(ap->ioaddr.data_addr);
..

I'm just catching up on a few things here now that holiday season is over.
In the above loop, I wonder if it might be better to only check status
every NN iterations, where NN > 1 (say, 16), to speed things up a fair amount (?).

Sure it's rare, but when it happens the entire system is probably stopped
waiting for us to recover, so speed might matter some.

Cheers