linux-kernel - Re: [PATCH 03/10] ide-atapi: teach ide atapi about drive->waiting_for

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Date:	Wed, 17 Sep 2008 09:32:08 -0700
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	petkovbb@...il.com
Cc:	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH 03/10] ide-atapi: teach ide atapi about drive->waiting_for_dma

On Wednesday 17 September 2008 03:05:12 Borislav Petkov wrote:
> Hi,
> 
> On Mon, Sep 15, 2008 at 08:15:51PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > On Sunday 14 September 2008 13:35:51 Borislav Petkov wrote:
> > > This is in preparation for converting ide-cd to generic code. The actual
> > > rewiring will be done later after the issue_pc/transfer_pc code knows all about
> > > ide-cd.
> > > 
> > > There should be no functional change resulting from this patch.
> > > 
> > > Signed-off-by: Borislav Petkov <petkovbb@...il.com>
> > > ---
> > >  drivers/ide/ide-atapi.c |   16 +++++++++++++---
> > >  1 files changed, 13 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
> > > index d557841..763acd7 100644
> > > --- a/drivers/ide/ide-atapi.c
> > > +++ b/drivers/ide/ide-atapi.c
> > > @@ -487,7 +487,13 @@ static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
> > >  	ide_startstop_t startstop;
> > >  	u8 ireason;
> > >  
> > > -	if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
> > > +	if ((drive->media == ide_cdrom || drive->media == ide_optical) &&
> > > +	    (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT)) {
> > > +		if (drive->dma)
> > > +			drive->waiting_for_dma = 1;
> > > +	}
> > 
> > We really want to do this for all ATAPI devices (as a bugfix).
> > 
> > > +	else if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY,
> > > +			       WAIT_READY)) {
> > 
> > IIRC similar check was removed from ide-cd so maybe this one
> > is also unnecessary?

[ actually, I mistook it for cdrom_start_packet_command() check ]

> Well, according to SFF8020, this chunk is for drives which don't support the
> "Accelerated DRQ" command packet DRQ type and those drives can set the DRQ bit
> as late as 10ms after receiving the PACKET command and I guess those are really
> old. I don't know whether it will be completely safe to remove it - for that

In this case we may as well do the wait on ide-cd devices.

Thanks,
Bart
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