On Thu, Jun 16, 2005 at 10:18:01AM +0000, Jochen Karrer wrote: > Hi, > I need an OHCI with Register and DMA descriptor byteorder separate > switchable. > > A PCI machine has little endian OHCI registers and little endian Endpoint > and transfer descriptors. For a non PCI OHCI (Netsilicon NS9750 ARM). I need > big endian OHCI registers with little endian DMA descriptors. > > The current implementation of big_endian() in ohci.h allows only to switch > both byteorders together. > So my proposal is to use two macros instead of one: > > #define big_endian_descriptors() .... > #define big_endian_registers() ....
Sounds reasonable. Please submit code when you get it working. :) > I'm not sure if isochronous transfers will work correctly in the current > implementation when big endian descriptors are used because the array hwPSW > is defined as 16 Bit: > > __hc16 hwPSW [MAXPSW]; > > But I think that big endian transfer descriptor means that hardware does a > swap32 and this can not be inverted by a > cpu_to_hc16 like in ohci-q.c. I suspect that the hwPSW[] fields will be > swapped pairwise when Big endian DMA descriptors are used. (hwPSW[0] with > hwPSW[1]....) This swapping is handled by ohci_hwPSWp(). Isochronous transfers do work on the two PPC OHCI implementations I've used. -Dale ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
