Well, I'm not sure I'd want to pollute the tree with this sort of
hack, but on the other hand it makes things work that wouldn't
otherwise.
Does anyone think it's a good idea to commit the following patch:
diff -urN /home/dgibson/kernel/linuxppc_2_4_devel/arch/ppc/mm/cachemap.c
linux-grinch/arch/ppc/mm/cachemap.c
--- /home/dgibson/kernel/linuxppc_2_4_devel/arch/ppc/mm/cachemap.c Thu Mar
14 13:49:01 2002
+++ linux-grinch/arch/ppc/mm/cachemap.c Wed Apr 3 11:51:30 2002
@@ -137,7 +137,18 @@
case PCI_DMA_NONE:
BUG();
case PCI_DMA_FROMDEVICE: /* invalidate only */
+#ifdef CONFIG_USB
+ /* The USB stack is broken in that it uses DMA buffers
+ on the stack which are on the stack and not
+ cacheline aligned. That means cache invalidates
+ before DMA transfers corrupt the stack on machines
+ without DMA-consistent cache. This is a nasty
+ workaround until the USB layer is fixed (apparently
+ done in 2.5). */
+ flush_dcache_range(start, end);
+#else
invalidate_dcache_range(start, end);
+#endif
break;
case PCI_DMA_TODEVICE: /* writeback only */
clean_dcache_range(start, end);
--
David Gibson | For every complex problem there is a
david at gibson.dropbear.id.au | solution which is simple, neat and
| wrong. -- H.L. Mencken
http://www.ozlabs.org/people/dgibson
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