On Wed, Jun 26, 2013 at 10:43:39PM +0200, Mariusz Grecki wrote: > The problem relates directly to the old one: > > http://thread.gmane.org/gmane.linux.usb.general/20816/focus=20850 > > The problem is, that usually (in fact all the time with one! exception > so far) the card is recognized by operating system as a full-speed (FS) > device not the high-speed (HS) one. This is weird, but once I have seen > it was recognized as high-speed device at my CPU. But that happened once > - I have no idea how and why. My suspicions is that during > initialization there is a kind of races that usually lead to full-speed > configuration. > > The FS operation is not enough since the card performance is limited or > (worse) the card is not possible to use since there are other USB > devices connected (not enough bandwidth). Perhaps the card realizes this and this is why it only offers up the lower speed? > One of the possible cause given in the mentioned thread was that the > card requires special initialization. This is not the case in my opinion > since I have seen it was initialized as a HS device with completely > different characteristics (more high precision and high sampling rate > modes of operation). The kernel only takes the device descriptor directly from the device, it doesn't have a way to change it. If you run 'usbmon' can you see anything different from when it is detected in the two different ways? > The computer to which the card is connected is uTCA embedded CPU with > high-speed USB hub. It runs Ubuntu 10.04 (Linux mskcpucmtb1 > 2.6.32-45-generic #102-Ubuntu SMP Wed Jan 2 22:38:04 UTC 2013 x86_64 > GNU/Linux). I have checked the same behavior with pure 3.9.2 kernel > compiled by me - for all cases FS device was configured. The only case > when the device was configured as HS device happened once with other > machine (not available at this moment). But it is not related to this > particular machine since I have tried many times on this machine later > and always it was configured as FS device. What happens if you don't use a USB hub and just plug it in directly to the root USB hub? How about on a "normal" desktop computer running Linux? 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
