Re: parport_pc

[Mitchell Blank Jr]

Alan Cox wrote:
> > For ISA and EISA like devices, NULL should be passed into
> > pci_alloc_consistent().  I know, we don't even get the
> > interfaces available when !CONFIG_PCI, that is something
> > to fix.
> 
> What about devices where ISA space is non coherent. They exist

The other thing that I think needs fixing is that passing NULL is
that you lose information.  I think we should define something
like:

	#define ISA_DMA ((struct pci_dev *) NULL)

for now, but later we could have something more like:

	struct pci_dev { dma_mask: 0xFFFFFF; } __isa_dma;
	#define ISA_DMA (&__isa_dma)

The reason is that the new mechanism supports a nice way to
control what part of memory (from the bus's perspective)
via the "pci_dev.dma_mask" value, which is an intellegent
replacement for GFP_DMA.  However, if we have multiple
"pci like" busses without per-device instances of
"struct pci_dev" then the current API wouldn't allow these
busses to have different memory needs.

-Mitch