On Tue, 16 Feb 2010 14:21:48 +0530 "Gadiyar, Anand" <gadiyar@xxxxxx> wrote: > > hcd->self.uses_dma = (dev->dma_mask != NULL); > > > > Is it easier to make sure that PIO devices don't have dev->dma_mask set? > > Not really. For instance, in the case of the DMA engine in the MUSB > controller in OMAP3, we can only use DMA with endpoints other than > EP0, and EP0 is what is used for control transfers. > > It's not PIO for all the endpoints or DMA for all of them. The HC driver does not have to be 100% truthful here. If the system is not HIGHMEM, HCD can easily set uses_dma to false yet use DMA by mapping buffers itself, without relying on the quoted code. On a HIGHMEM system, block layer will bounce-buffer data in such case. Hopefuly not a problem for ARM? All network stack drivers work that way, BTW. -- Pete -- 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
