Re: [PATCH] pci_alloc_consistent in an interrupt context

On Thu, Jun 13, 2002 at 05:51:56PM -0700, Tom Rini wrote:

On Fri, Jun 14, 2002 at 10:45:39AM +1000, David Gibson wrote:

quoted

On Thu, Jun 13, 2002 at 05:38:07PM -0700, Tom Rini wrote:

[snip]

quoted

quoted

Er, the problem of setting dma_handle twice?

Well, it fixes that and as a bonus gets rid of the ifdefs in
pci_{alloc,free}_consistent() and means that if we ever port a driver
using consistent_{alloc,free}() to a processor that *is* cache
coherent it will Just Work.

In theory at that point OCP would either have its API fully flushed out
or be applied nicely on top of the generic driver work in 2.5 and it
would just work anyhow :)

Well at the moment OCP drivers call consistent_alloc() directly which
would always fail on cache-coherent processors.

quoted

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My only concern is that are things still consistent on non consistent
procs?

Absolutely - no change to the code path at all on non cache coherent
processors.

So kmalloc/kfree are equivilent to __get_free_pages/free_pages ?

Read that again: on *non* cache coherent processors the code path is
the same.  kmalloc() vs. __get_free_pages() is a problem for
processors which *are* cache coherent.

--
David Gibson			| For every complex problem there is a
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.  -- H.L. Mencken
http://www.ozlabs.org/people/dgibson

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