On Thu, 18 Mar 2004, Matthias Andree wrote: > Some questions: > > 1. Should configuration changes be locked out while bulk transfers are > in progress?
That's not a simple question. The short answer is that configuration changes are already locked out while an individual bulk transfer is in progress, assuming you're talking about doing things with usbfs/libusb. If a whole sequence of bulk transfers takes place, there's nothing to prevent a configuration change poking in between two of those transfers. Then the transfers submitted after the change would fail -- or least, they should fail and if usbfs works correctly they will (usbfs still has some bugs in it). In general, we don't want to prevent configuration changes while transfers are taking place. > 2. Leaving configuration issues aside, another difference in hardware is > that the VIA KT133 (82C686A) I had no troubles supported USB 1.1 > only, whereas the KT600 (8237) also supports USB 2.0, hence EHCI. I > don't know about these companionships between EHCI and UHCI ports - > are the ports virtually "handed over" between EHCI and UHCI depending > on whether the bus talks 1.5, 12 or 480 Mbit/s? That's almost right. At the time a device is plugged in to the computer, the EHCI controller detects what speed the device can run at. If it can run at high speed (480 Mb/s) the EHCI controller handles it. If it can only run at full (12 Mb/s) or low (1.5 Mb/s) speed, the connection is handed over to the companion UHCI controller. The same physical port is electrically connected to both controllers, but only one of them talks to it at any time. > 2b. Or might speed negotiations/switches cause hotplug events in 2.6? They don't. They occur at a hardware level before the system is aware of anything. When the connection sequence has completed, then a hotplug event is generated regardless of the conection speed. Once the connection is established, its speed cannot change. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
