Regarding consistent_alloc

[Joakim Tjernlund]

>
> On Fri, Dec 06, 2002 at 03:25:48PM +0100, Joakim Tjernlund wrote:
> > If you implement the performance improvement I suggested earlier, I don't think
> > you need them. Another thing with consistent_xxx() is that you can not use
> > __pa() and __va() on addresses returned by the consistent_alloc et. al.
>
> Um, well if you are doing a consistent_alloc() then surely you are
> keeping the dma_handle around which is your physical address.  If you
> want the kernel virtual address then you can apply __va to that.  So,
> you have the cache inhibited mapping in vmalloc space returned to you,
> the physical address provided in dma_handle, and a kernel virtual address
> that can be trivially generated.

m8xx_cpm_hostalloc() does not keep the DMA handle and __pa() does not work
on addresses returned by m8xx_cpm_hostalloc(). I just found that out the
hard way when upgrading from MV 2.4.2 to linuxppc_2_4_devel 2.4.20. My SPI driver
hung as soon you tried to read something.

Not sure about __va() but there is a comment in 8xx_io/enet.c that it does not work
anymore.

Perhaps this is so only for early calls to consistent_alloc(during the init phase)?

  Jocke

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


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