[PATCH][v2] driver/FSL SATA:Fix wrong Device Error Register usage

[Kushwaha Prabhakar-B32579]

> -----Original Message-----
> From: Benjamin Herrenschmidt [mailto:benh at kernel.crashing.org]
> Sent: Wednesday, March 02, 2011 8:56 AM
> To: Kushwaha Prabhakar-B32579
> Cc: linuxppc-dev at lists.ozlabs.org; meet2prabhu at gmail.com; Kalra Ashish-
> B00888
> Subject: Re: [PATCH][v2] driver/FSL SATA:Fix wrong Device Error Register
> usage
> 
> On Mon, 2011-02-21 at 15:27 +0530, Prabhakar Kushwaha wrote:
> > When a single device error is detected, the device under the error is
> > indicated by the error bit set in the DER. There is a one to one
> > mapping between register bit and devices on Port multiplier(PMP) i.e.
> > bit 0 represents PMP device 0 and bit 1 represents PMP device 1 etc.
> 
> It might help to send those patches to the linux-ide mailing list and
> appropriate libata maintainers in addition to CC'ing linuxppc-dev.
> 
Thanks Benjamin!!
I will take care your point in near future.

--Prabhakar

> > Current implementation treats Device error register value as device
> > number not set of bits representing multiple device on PMP. It is
> > changed to consider bit level.
> > No need to check for each set bit as all command is going to be
> aborted.
> >
> > Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
> > Signed-off-by: Ashish Kalra <B00888 at freescale.com>
> > ---
> >  git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
> > (branch master)
> >
> >  Changes for v1: Incorporated David Laight's comment
> >  	- Single usage of ffs()
> >
> >  Changes for v2: Incorporated David Laight's comment
> >  	- Changed type of dev_num to unsigned
> >
> >  drivers/ata/sata_fsl.c |    6 ++++--
> >  1 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c index
> > b0214d0..895771c 100644
> > --- a/drivers/ata/sata_fsl.c
> > +++ b/drivers/ata/sata_fsl.c
> > @@ -1040,12 +1040,14 @@ static void sata_fsl_error_intr(struct
> > ata_port *ap)
> >
> >  		/* find out the offending link and qc */
> >  		if (ap->nr_pmp_links) {
> > +			unsigned int dev_num;
> >  			dereg = ioread32(hcr_base + DE);
> >  			iowrite32(dereg, hcr_base + DE);
> >  			iowrite32(cereg, hcr_base + CE);
> >
> > -			if (dereg < ap->nr_pmp_links) {
> > -				link = &ap->pmp_link[dereg];
> > +			dev_num = ffs(dereg)-1;
> > +			if (dev_num < ap->nr_pmp_links) {
> > +				link = &ap->pmp_link[dev_num];
> >  				ehi = &link->eh_info;
> >  				qc = ata_qc_from_tag(ap, link->active_tag);
> >  				/*
> 
>