On Tue, Jan 05, 2016 at 10:49:49PM -0800, Christoph Hellwig wrote: > This is a completely broken usage of the mmap interface. if you use > mmap on a device file you must use the actual mmap for the data > transfer.
Really? V4L does exactly the same thing, from what I can see. It's just a way of allocating memory with specific properties, roughly similar to hugetlbfs. > Our interface for zero copy reads/writes is O_DIRECT, and that requires > not special memory allocation, just proper alignment. But that assumes you are using I/O using read()/write(). There's no way you can shoehorn USB isochronous reads into the read() interface, O_DIRECT or not. /* Steinar */ -- Software Engineer, Google Switzerland -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
