On Mon, Nov 08, 2010 at 12:20:30AM -0600, Gadiyar, Anand wrote:
The Inventra DMA engine in version 1.8 and later of the MUSB controller cannot handle DMA addresses that are not aligned to a 4 byte boundary. It ends up ignoring the last two bits programmed in the DMA_ADDR register. This is a deliberate design change in the controller and is documented in the programming guide. Earlier versions of the controller could handle these accesses just fine. Fail dma_channel_program if we see an unaligned address when using the newer controllers, so that the caller can carry out the transfer using PIO mode. (Current callers already have this backup path in place). Signed-off-by: Anand Gadiyar <gadiyar@xxxxxx> Tested-by: Ming Lei <tom.leiming@xxxxxxxxx> Cc: Felipe Balbi <balbi@xxxxxx> Cc: Ajay Kumar Gupta <ajay.gupta@xxxxxx> Cc: Mike Frysinger <vapier@xxxxxxxxxx>
applied, thanks (I thought we already had that in mainline :-p) Note to self: later we might want to use a bounce buffer instead of simply failing DMA. Gotta measure what's faster: use PIO or dma_alloc_coherent() + memcpy() -- balbi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
