Re: [PATCH-RFC 07/10] parisc: switch to GENERIC_PCI_IOMAP

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Dec 04, 2011 at 08:32:24AM -0600, James Bottomley wrote:
> On Sun, 2011-12-04 at 16:30 +0200, Michael S. Tsirkin wrote:
> > On Sun, Dec 04, 2011 at 08:22:34AM -0600, James Bottomley wrote:
> > > On Sun, 2011-12-04 at 12:48 +0200, Michael S. Tsirkin wrote:
> > > > On Thu, Nov 24, 2011 at 10:19:34PM +0200, Michael S. Tsirkin wrote:
> > > > > parisc copied pci_iomap from generic code, probably to avoid
> > > > > pulling the rest of iomap.c in.  Since that's in
> > > > > a separate file now, we can reuse the common implementation.
> > > > > 
> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > > 
> > > > Sorry to nag, any ACKs/NACKs on the parisc part?
> > > > I intend to send this to Linus if there are no
> > > > objections. Thanks!
> > > 
> > > Next time, send the patch to linux-arch or linux-parisc ... it helps to
> > > get people to review it. Although this one looks completely trivial,
> > > unless I'm missing something?
> > 
> > I think it's trivial but I don't have the setup to even compile it so
> > depend on someone to ack.
> > 
> > > Obviously there was a bit of a brain fart when this was done: the parisc
> > > piece shouldn't be a copy of the generic code: we don't have native i/o
> > > ports and emulation is pretty expensive, so we should prefer
> > > IORESOURCE_MEM over IORESOURCE_IO when both are available  ... but even
> > > on x86, memory mapping is faster (although not by the order of magnitude
> > > it is on parisc), so it looks like you could fix this in the generic
> > > code.
> > > 
> > > James
> > 
> > AFAIK, on PCI a resource is either IO or MEM, but never both.
> > What am I missing?
> 
> Could be ... I know we've had issues in the past with standard drivers
> like the sym53c8xx which map via both and operate far less efficiently
> over I/O ... but that could have been different bars I suppose (it's so
> long ago that I can't remember).

Probably, it looks like it has both mmio and io:

drivers/scsi/sym53c8xx_2/sym_glue.c

#ifdef CONFIG_SCSI_SYM53C8XX_MMIO
        if (device->mmio_base)
                device->s.ioaddr = pci_iomap(pdev, 1,
                                                pci_resource_len(pdev, 1));
#endif
        if (!device->s.ioaddr)
                device->s.ioaddr = pci_iomap(pdev, 0,
                                                pci_resource_len(pdev, 0));


so ... ACK?

> 
> James
> 

-- 
MSt