Re: Busmaster DMA broken in 2.4.18 on Alpha

["David S. Miller" <davem@redhat.com>]

   From: Jay Estabrook <Jay.Estabrook@compaq.com>
   Date: Mon, 11 Mar 2002 10:02:00 -0500
   
   Since ISA devices don't have pci_dev structures, there's (currently)
   no way to pass an ISA device-dependent DMA mask to the IOMMU routines.
   Perhaps there needs to be an addition to the API that would allow
   for this (pci_set_isa_device_dma_mask()) ???

What you could do currently is whip up a dummy pci_dev structure with
the mask you want and pass that into the PCI dma routines.  So you
could, for example, default to 24-bit DMA mask when you get "NULL"
as pci_dev, but cook up a special one using a 32-bit DMA mask for the
floppy ISA device in question.

The idea in 2.5.x is to move to a generic struct device, at which time
something like this can be done much more cleanly.