2010/11/8 Felipe Balbi <balbi@xxxxxx>: > 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 Suggest the revised patch "usb: musb: gadget: Unmapping the dma buffer when switching to PIO mode" [1] is applied too, otherwise some odd data inconsistent or corruption things may be triggered when fallback to PIO, which will be very frequent in g_ether. [1], http://marc.info/?l=linux-usb&m=128532510705381&w=2 > > (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() > thanks, -- Lei Ming -- 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
