Re: [PATCH 0/19] clean ups on the drivers

[James Bottomley <James.Bottomley@SteelEye.com>]

On Tue, 2007-05-15 at 10:01 +0100, Christoph Hellwig wrote:
> On Mon, May 14, 2007 at 05:39:06PM +0200, Stefan Richter wrote:
> > FUJITA Tomonori wrote:
> > >> > There are two patches for each driver, removing the non-use-sg code
> > >> > and converting to use the accessors.
> > ...
> > > I merged the two. And I finished cleaning up 35 drivers in total.
> > > 
> > > git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-bidi.git cleanups
> > 
> > According to what I see via gitweb, at least usb-storage, ieee1394/sbp2,
> > and firewire/fw-sbp2 weren't treated yet.  If somebody does so for the
> > latter two:  The shost->shost_gendev.parent has to be changed for
> > scsi_dma_{un}map.  I don't know if this can be done without breaking
> > anything.
> 
> That means they should not be converted to these helpers for now.
> 
> Personally I'd still love to have the dma mapping routines to work on
> any given struct device but walking up the parent chain until an iommu
> is found, but that was vetoed when first proposed.

Er ... I really hope not ... that's exactly how the parisc iommu
platform code works ... and why I designed the generic dma mapping this
way.  The key thing parisc needed was the ability to walk up different
busses until it found the iommu (for example the pci bus -> dino -> GSC
-> IOMMU) which it does by traversing the dev->parent; However, I didn't
mandate working this way for other architectures.

James