On Tue, 25 Dec 2012, Xiaofan Chen wrote: > On Tue, Dec 25, 2012 at 12:28 AM, Alan Stern <st...@rowland.harvard.edu> > wrote: > > (Although I don't believe Apple uses > > UHCI components in their machines.) > > Supposedly Apple uses Intel chipsets now and will have UHCI along with > the EHCI controller (Intel and Via usually use UHCI and others use OHCI, > as per Wikipedia).
That's what I was referring to... I haven't yet seen any Apple computers using an Intel chipset. > Ref: http://en.wikipedia.org/wiki/Host_controller_interface_(USB,_Firewire) > > But indeed you are right I do not see UHCI components in my Mac Mini 2011. > Root <class IORegistryEntry> > 1: EHCI Root Hub Simulation@1D,7 <class IOUSBRootHubDevice> > 2: HubDevice@fd100000 <class IOUSBHubDevice> > 3: IR Receiver@fd110000 <class IOUSBDevice> > 4: PROLiNK PCC3220@fd130000 <class IOUSBDevice> > 1: EHCI Root Hub Simulation@1A,7 <class IOUSBRootHubDevice> > 2: HubDevice@fa100000 <class IOUSBHubDevice> > 3: BRCM20702 Hub@fa110000 <class IOUSBHubDevice> > 6: Bluetooth USB Host Controller@fa113000 <class IOUSBDevice> > 4: USB2.0 Hub@fa130000 <class IOUSBHubDevice> > 7: Amontec JTAGkey-2@fa131000 <class IOUSBDevice> > 8: usb serial converter@fa133000 <class IOUSBDevice> > 9: USB Receiver@fa134000 <class IOUSBDevice> > 10: FT232R USB UART@fa132000 <class IOUSBDevice> > 5: USB Keyboard@fa120000 <class IOUSBDevice> That's understandable if Apple has recently switched to using Intel chipsets. Intel stopped including UHCI controllers some time ago; instead they attach an on-board hub to each EHCI controller. > > On the other hand, it doesn't require much agility to move a mouse > > faster than 16 pixels/second. But I agree that HID devices do not > > need to e polled 1000 times per second, as a general rule. In fact, > > many HID devices run at low speed rather than full speed, and USB > > demands that low-speed devices may not have polling intervals less than > > 10 ms. > > That is true. But for generic USB device which use HID to avoid driver > under Windows, full speed USB with 1ms bInterval will help. If there are high > speed high bandwdith HID device, then the speed can go to 24MB/sec > and it can replace isochronous device. But Microsoft does not support > high speed high bandwidth interrupt endpoint for Windows, not so sure > about Mac OS X and Linux. Linux does. I don't know about OS-X. > Reference: > http://www.osronline.com/showthread.cfm?link=161236 > http://www.winvistatips.com/usbehci-sys-bug-high-bandwidth-interrupt-endpoints-t182832.html > http://www.cypress.com/?id=4&rID=31709 > http://www.lvr.com/usbfaq.htm > > And actually Windows HID driver does not support alternative interface, > this limit high speed HID device to top at 64Bytes/125us = 512KB/sec > speed. If not for this limitation, high speed HID device (up to > 24MB/sec for high speed high bandwidth, 1024 Bytesx 3 /125us; > 8MB/sec without high bandwidth interrupt endpoint, 1024Byte/125us). > > Ref: > http://www.lvr.com/forum/index.php?topic=559.0 > http://www.cygnal.org/ubb/Forum9/HTML/001121.html Another good reason for manufacturers not to use the HID class unless the device really is meant to be used as a Human Interface. Alan Stern ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ libusbx-devel mailing list libusbx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libusbx-devel
