Re: [PATCH/RFC] libata-dev: handle ERR=1 DRQ=1

[Jeff Garzik <jgarzik@pobox.com>]

Albert Lee wrote:
> handle ERR=1 DRQ=1 for PIO protocol
> 
> Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
> ---
> 
> Some PIO read commands might set DRQ=1 alone with ERR=1.
> Under such situation, the data block should be transferred even if err=1.
> 
> This patch adds extra logic to HSM_ST_ERR to handle the required
> data transfer.
> 
> BTW, also found the following work in progress:
> "Disable Data Transfer after Error Detection"
> http://t13.org/docs2006/dt1825Lr3-DDT_TR.pdf
> If this feature is turned on, then DRQ will be guaranteed 0 when ERR=1
> which would simplify the PIO error handling.
> 
> Patch against the irq-pio branch.
> Need your review and advice, thanks.

If DRQ==1 then the error register and ATA_ERR should be considered 
irrelevant.  I agree with Eric, that's more of a "don't touch it, other 
than to SRST it" situation.

	Jeff