On Sun, 22 Nov 2009, Simon Arlott wrote: > On 18/11/09 22:25, Alan Stern wrote: > > On Wed, 18 Nov 2009, Simon Arlott wrote: > >> > What happens with other sorts of devices, such as a USB flash drive? > >> > >> I can write a 10MB file to an USB flash drive over OHCI, and umount+sync > >> takes around 13 seconds. > > > > Yes, that's about right. It leads me to wonder if something funny is > > going on with the device, or least with the firmware-loading part of > > it. Odd that it works differently with UHCI and OHCI, though. There > > shouldn't be any differences visible to the device. You don't have > > anything else attached to the same bus, do you? > > Yes, but not in use and I could disconnect everything to test it. > > core/hcd.c has an interesting comment in usb_hcd_check_unlink_urb(): You mean usb_hcd_poll_rh_status(). > /* The USB 2.0 spec says 256 ms. This is close enough and won't > * exceed that limit if HZ is 100. The math is more clunky than > * maybe expected, this is to make sure that all timers for USB devices > * fire at the same time to give the CPU a break inbetween */ > > I'll try increasing the frequency of this timer too. It shouldn't make any difference; that timer is used with OHCI only in exceptional circumstances (like immediately after a device is plugged in or unplugged), not during normal operation. But maybe something strange is going on. You could add a printk in ohci_hub_status_data(), which is the routine that timer ends up calling. 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
