Re: [patch 29/30] sata_nv: don't read shadow registers when in ADMAmode

[Robert Hancock]

Jeff Garzik wrote:
> akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> > From: Robert Hancock <hancockr@xxxxxxx>
> >
> > Reading from the ATA shadow registers while we are in ADMA mode may cause
> > undefined behavior.  Don't read the ATA status register when completing
> > commands for this reason, it shouldn't be needed as the controller will
> > notify us if the command failed.  Also, don't allow commands with result
> > taskfile requested to execute in ADMA mode, since that requires accessing
> > the shadow registers.  We also still need to override tf_read since 
> > libata
> > will read the result taskfile on a command failure, and we need to go 
> > into
> > port register mode before allowing this.
> >
> > Signed-off-by: Robert Hancock <hancockr@xxxxxxx>
> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > ---
> >
> >  drivers/ata/sata_nv.c |   33 ++++++++++++++++++++-------------
> >  1 file changed, 20 insertions(+), 13 deletions(-)
>
> Robert, do you think this should be pushed into #upstream-fixes 
> (2.6.21-rc)?
>
> I lean towards "yes", since it is a needed-by-hardware fix, but I also 
> am interested in testing feedback since it is so late in the 2.6.21-rc 
> game.

I would lean toward that as well, but it would be good to get some 
testing from some sata_nv ADMA users to make sure it doesn't do anything 
funny for them..

--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page: http://www.roberthancock.com/

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