Re: [PATCH] ibmvscsi driver - sixth version

[Dave Boutcher]

On 31 Mar 2004 18:39:57 -0500, James Bottomley 
<James.Bottomley@xxxxxxxxxxxx> wrote:
> > > 14) why are you faking a PCI bus?  The following is very, very wrong:
> > >
> > > +static struct pci_dev iseries_vscsi_dev = {
> > > +	.dev.bus = &pci_bus_type,
> > > +	.dev.bus_id = "vscsi",
> > > +	.dev.release = noop_release
> > >
> > > Did I mention "very" wrong?  :)
> > Because for iseries it is implemented in the pci code.  While it may
> > look wrong, it is actually correct.  Check out
> > arch/ppc64/kernel/iSeries_iommu.c and arch/ppc64/kernel/dma.c.
> > This device has to have dev->bus == &pci_bus_type otherwise the
> > dma_mapping_foo functions won't work correctly.
>
> Erm, something is very wrong in the iSeries code then.  This
> iseries_vio_device is a struct device.  As such, it should contain all
> the information it needs for the DMA API to act on it without performing
> silly pci device tricks.
>
> This looks like it's done because the iseries should be converted to the
> generic device infrastructure, but in fact it's not.  Since the generic
> API has been around for over a year and was designed to solve precisely
> these very problems it needs fixing rather than trying to work around it
> in a driver.
There will always be 1 (no more, no less) of these struct devices in the
system, so I'll move the definition of this into iSeries_iommu and then
just reference it from the driver.  I think that should abstract things
sufficiently.

Dave B
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