Re: [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O supportproperly

[Sergei Shtylyov]

Hello.

Jeff Garzik wrote:

> > This patch fixes ata_id_has_dword_io to return 1 (supported) if
> > the drive is compliant to ATA2 or newer and evaluates the config
> > word for older drives.

> > Signed-off-by: Mario Schwalbe <schwalbe@xxxxxxxxxxxxxxxxx>

> > diff --git a/include/linux/ata.h b/include/linux/ata.h
> > index a53318b..d0d6a9c 100644
> > --- a/include/linux/ata.h
> > +++ b/include/linux/ata.h
> > @@ -700,12 +700,12 @@ static inline int ata_id_has_tpm(const u16 *id)

> >  static inline int ata_id_has_dword_io(const u16 *id)
> >  {
> > -    /* ATA 8 reuses this flag for "trusted" computing */
> > -    if (ata_id_major_version(id) > 7)
> > -        return 0;
> > -    if (id[ATA_ID_DWORD_IO] & (1 << 0))
> > -        return 1;
> > -    return 0;
> > +    /* This flag is defined up to ATA1 and deprecated since then
> > +       (ATA 8 reuses this flag for "trusted" computing). */
> > +    if (ata_id_major_version(id) <= 1)
> > +        return (id[ATA_ID_DWORD_IO] & (1 << 0)) != 0;
> > +    /* later revision drives support DWORD I/O just fine */
> > +    return 1;

> This seems like a risky assumption...

   Not at all, I think. It's total mystery how "DWORD I/O" could've been even 
(not) supported by a *drive* at all. Support of "DWORD I/O" is a property of 
the PATA controller. Frankly speaking, I don't think that this function is at 
all useful...

>     Jeff

MBR, Sergei
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