Re: Suggestions for how to remove bus_to_virt()

From: Stefan Richter
Date: Thu Jul 13 2006 - 03:47:10 EST


David Miller wrote:
> If you need device level DMA mapping semantics, create them for your
> device type. This is what USB does, btw.

Ralph,
two other examples where drivers provide some sort of address lookup are:

- drivers/ieee1394/dma.[hc]
AFAIK this deals with housekeeping of ringbuffers as used by
1394 controllers for isochronous transmit and receive. Users of
this little API are dv1394, video1394, ohci1394.

- patch "dc395x: dynamically map scatter-gather for PIO" by
Guennadi Liakhovetski,
http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cdb8c2a6d848deb9eeefffff42974478fbb51b8c
This mapping is not specific to SCSI. The user is a driver which
mixes PIO and DMA.

I don't know if these have any similarity to your requirements though.

(I too need to come up with either a portable replacement of bus_to_virt
or with a fundamentally different implementation but haven't started my
project yet. This occurrence of bus_to_virt is in drivers/ieee1394/sbp2
but #ifdef'd out by default.)
--
Stefan Richter
-=====-=-==- -=== -==--
http://arcgraph.de/sr/
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