On Mon, 2007-11-19 at 13:43 -0800, Roland Dreier wrote: > > I've been debugging various issues on the PowerPC 44x embedded > > architecture which happens to have non-coherent PCI DMA. > > > > One of the problem I'm hitting is that one really need to enforce > > kmalloc alignement to cache lines or bad things will happen (among > > others with USB), for some reasons, powerpc failed to do so, I fixed it. > > Heh... I hit the same problem literally 5 years ago: > http://lwn.net/Articles/1783/ > > I implemented the __dma_buffer annotation: > http://lwn.net/Articles/2269/ > > But DaveM said we should just use the PCI pool code instead: > http://lwn.net/Articles/2270/ Heh, well... In this case, DaveM just proposed something akin to your __dma_buffer :-) On the other hand, after discussing with James, it looks like we'll just be reverting the patch that removed the kmalloc of the sense buffer since non cache-coherent archs are supposed to enforce kmalloc alignment to cache lines. __dma_buffer still seems like a good thing to have if too many other drivers are hitting that but for this specific problem, it's not the approach that we'll be taking. Cheers, Ben. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
