Re: [PATCH v5 02/12] libata: bind the Linux device tree to theACPI device tree

[Lin Ming]

On Wed, 2012-06-20 at 16:50 -0700, Dan Williams wrote:
> On Sun, Jun 17, 2012 at 11:25 PM, Lin Ming <ming.m.lin@xxxxxxxxx> wrote:
> > From: Matthew Garrett <mjg@xxxxxxxxxx>
> >
> > Associate the ACPI device tree and libata devices.
> > This patch uses the generic ACPI glue framework to do so.
> >
> > Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
> > Signed-off-by: Holger Macht <holger@xxxxxxxx>
> > Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> > ---
> >
> > Changelog:
> >
> > - fixed crash reported at https://lkml.org/lkml/2012/2/24/2 (Aaron Lu)
> > - rename is_pci_ata to compat_pci_ata (Alan Cox)
> >
> >  drivers/acpi/glue.c       |    4 +-
> >  drivers/ata/libata-acpi.c |  125 +++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/ata/libata-core.c |    3 ++
> >  drivers/ata/libata.h      |    4 ++
> >  4 files changed, 134 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
> > index 1564e09..18d6812 100644
> > --- a/drivers/acpi/glue.c
> > +++ b/drivers/acpi/glue.c
> [..]
> > +static int ata_acpi_bind_host(struct device *dev, int host, acpi_handle *handle)
> > +{
> > +       struct Scsi_Host *shost = dev_to_shost(dev);
> > +       struct ata_port *ap = ata_shost_to_port(shost);
> > +
> > +       if (ap->flags & ATA_FLAG_ACPI_SATA)
> > +               return -ENODEV;
> > +
> > +       *handle = acpi_get_child(DEVICE_ACPI_HANDLE(dev->parent), ap->port_no);
> > +
> > +       if (!*handle)
> > +               return -ENODEV;
> > +
> > +       return 0;
> > +}
> 
> I think this patch should be squashed with patch 4, right?  That is if
> we keep the hard-coded ->parent chasing...

Right. Will merge patch 4.

> 
> > +static int ata_acpi_find_device(struct device *dev, acpi_handle *handle)
> > +{
> > +       unsigned int host, channel, id, lun;
> > +
> > +       if (sscanf(dev_name(dev), "host%u", &host) == 1) {
> > +               if (!compat_pci_ata(dev->parent))
> > +                       return -ENODEV;
> > +
> > +               return ata_acpi_bind_host(dev, host, handle);
> > +       } else if (sscanf(dev_name(dev), "%d:%d:%d:%d",
> > +                       &host, &channel, &id, &lun) == 4) {
> > +               if (!compat_pci_ata(dev->parent->parent->parent))
> > +                       return -ENODEV;
> 
> ...this looks like it should be using a dev_to_ata_port() helper which
> like dev_to_shost() skips the need to remember just how many parents
> until we get back to our ata_port, scsi_host, etc.

Oh, no.

compat_pci_ata checks whether the controller(rather than shost or ata
port) is pci SATA/IDE controller.

As in patch 4:
compat_pci_ata(dev->parent->parent->parent->parent)

The "dev" is ata port, and dev->parent->parent->parent->parent points to
the controller dev.

This looks ugly. How about add two helpers?
shost_to_controller(dev) and ata_port_to_controller(dev)

Thanks,
Lin Ming

> 
> --
> Dan


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