On Mon, 30 Jul 2007, Alex Chiang wrote: > Hello, > > How are ports numbered/ordered in the case of an EHCI controller > with a companion controller? > > Example: N_PORTS = 6 > > AND > N_CC = 2 > N_PCC = 3 > > OR PORTROUTE[] = 1,1,1,2,2,2 > > Would give a routing configuration of: > > EHCI port 1 = OHCI1 port 1 (not 2 or 3) > EHCI port 2 = OHCI1 port 2 (not 1 or 3) > EHCI port 3 = OHCI1 port 3 (not 1 or 2) > EHCI port 4 = OHCI2 port 1 etc. > EHCI port 5 = OHCI2 port 2 > EHCI port 6 = OHCI2 port 3 > > Is this assumption correct?
Yes. Except that the companion controllers might not be OHCI-1 and OHCI-2 -- they might be OHCI-3 and OHCI-4. In fact, something like that is certain to happen if you have more than one EHCI controller. > The broader context of this question is, on ia64 systems, certain > EFI drivers only support 1.1. So imagine a scenario where one > might have two USB cdroms attached to the system, but only want > to boot off of one (or maybe something more plausible, a USB hard > drive and a USB cdrom, and are booting off the CD). > > When the bootloader hands off to the kernel and says "use the > device attached to OHCI controller N, port M" will the value of M > change when the EHCI driver takes over? There's no way for the bootloader to tell the kernel that. The most it can do is something like "root=/dev/sr0". It's up to the udev scripts in the kernel's initramfs to make sure that the correct device is mapped by /dev/sr0. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
