On Tue, Mar 22, 2011 at 05:26:01PM +1100, Benjamin Herrenschmidt wrote: > Hi Greg ! > > I recently noticed that the output from lsusb was utterly wrong on PPC > for 16-bit fields (like bad endianess :) > > Digging a bit I noticed a couple of things: > > - My distro (ubuntu, yeah I know how much you love them) variant of > lsusb does: > > if (__BYTE_ORDER == __LITTLE_ENDIAN) > #define le16_to_cpu(x) (x) > #elif (__BYTE_ORDER == __BIG_ENDIAN) > #define le16_to_cpu(x) bswap_16(x) > #else > #error missing BYTE_ORDER > #endif What version of usbutils is this? > when reading a 16-bit field from a descriptor > > - "Upstream" usbutils does: > > #define le16_to_cpu(x) libusb_cpu_to_le16(libusb_cpu_to_le16(x)) > > Now, the later is obviously crackpot :-) It's really basically a nop > right ? Yes it is. :) I commented on this a while ago but I got the report that it worked, and no one else had a BE system, I didn't know what to do, so I left it. > The fun thing is, this is the -right- thing to do (tho I haven't built & > tried that version yet). The trick is that descriptor structures parsed > by libusb using usb_parse_descriptor and the "w" format will already > have been appropriately byteswapped by libusb itself. > > So lsusb should never have to do that swapping again (and gives a bad > example to other programs). Good point, I'll drop this entirely from the current version as we should be fine now. thanks, greg k-h -- 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
