On Wed, 7 Apr 2010, Greg KH wrote: > Yeah, I really don't want to have to change every driver in different > ways just depending on if someone thinks it is going to need to run on > this wierd hardware. It's not weird hardware, as far as I know. It's just a 64-bit system with a 32-bit USB host controller. (And remember, while there are 64-bit EHCI controllers, there are not any 64-bit OHCI or UHCI controllers. So whenever somebody plugs a full-speed or low-speed device into a 64-bit machine, they will face this problem. It's like the old problem of ISA devices that could only do DMA to addresses in the first 16 MB of memory -- what the original GFP_DMA flag was intended for.) > Alan, any objection to just using usb_buffer_alloc() for every driver? > Or is that too much overhead? I don't know what the overhead is. But usb_buffer_alloc() requires the caller to keep track of the buffer's DMA address, so it's not a simple plug-in replacement. In addition, the consistent memory that usb_buffer_alloc() provides is a scarce resource on some platforms. Writing new functions is the way to go. 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
