problem with pci_alloc_consistent (it does work)

Matt Porter porter at cox.net
Wed Sep 18 09:16:51 EST 2002


On Tue, Sep 17, 2002 at 02:24:35PM -0400, Waqar Ahmad wrote:
> Found the problem I was using phys_to_virt(..) to convert the
> physical address to virtual. Once I fixed that everything seems
> to be working now. so

Anybody confused by this should read and understand
Documentation/IO-mapping.txt.  virt_to_phys/phys_to_virt
and virt_to_bus/bus_to_virt are only defined for usage on
system memory.  This means statically mapped kernel memory.
The only way to reliably (cross platform) get a physical
address from pci_alloc_consistent is to hold on to your
dma_handle.  This has been covered a number of times on lkml
with DavidM and might even be in the current DMA-mapping.txt
by now...but I doubt it. :)

Regards,
--
Matt Porter
porter at cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.

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