linux-kernel - Re: ata_sff_drain

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Message-ID: <20100818162329.GC3029@gaiman.synerway.com>
Date:	Wed, 18 Aug 2010 18:23:29 +0200
From:	Pascal GREGIS <pgs@...erway.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: ata_sff_drain_fifo

Alan Cox a écrit, le mer 18 aoû 2010 à 12:44:12 :
> > so I guess when status is 0xD0, ATA_DRQ is not set but ATA_BUSY is.
> > It would explain why in my case it doesn't drain anything before trying to reset.
> > 
> > Would it be of any interest to drain the fifo also when the ATA_BUSY flag is on, not only the ATA_DRQ ?
> 
> If the drive has the busy flag set it is busy, all we can do is wait for
> it and if that fails try to reset it. The FIFO drain handles a specific
> case where the two ends disagree about the amount of data expected, and
> often lets us avoid a reset.
Ok. I also noticed that qc->dma_dir=DMA_TO_DEVICE which also prevents the draining.
I thought it could be a solution for certain problems like mine where the device is busy but the reset doesn't work which brings to a blocking point, but no.

Pascal

> 
> Alan
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