Felipe: There's a comment in message.c:usb_sg_init() about some systems needing to revert to PIO when DMA is temporarily unavailable. Does this refer to the musb drivers? Or if not, do you know which drivers it does refer to? This is something we have to be careful about. The CPU generally isn't allowed to access buffers while they are mapped for DMA. If the controller driver needs to use PIO instead of DMA, then it will have to unmap the buffers first. I have been working on map_urb_for_dma() and unmap_urb_for_dma(), and it seems like a good idea to EXPORT the unmap routine so that HCDs could call it when they need to revert to PIO. And of course, we will also need to add changes for drivers that have to use PIO for control transfers but can use DMA for other transfer types. Alan Stern -- 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
