Armin wrote: > > David Gibson wrote: > > 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 > > > > > > > > > > > > Ah yes, We have done something simular (internally) and had the same > reservations. This will help me with the ocp usb drivers i am working > on. I would like to see some way of reminding us that this was done. > let say a config option for 4xx_usb_dma_workarround.
Not just 4xx processors - this applies to all processors that require CONFIG_NOT_COHERENT_CACHE. -Frank -- Frank Rowand <frank_rowand at mvista.com> MontaVista Software, Inc ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
