On Tue, Feb 05, 2008 at 04:48:38PM -0500, Alan Stern wrote: > On Tue, 5 Feb 2008, David Brownell wrote: > > > The reason to try powering off the ports is that, well, the system is > > shutting down. Why waste (potentially battery) power? Whatever runs > > next can turn it back on if it wants. And if PPS isn't set, then trying > > to clear the per-port power-enabled flag is supposed to be a NOP. > > There's another reason for powering off the ports during shutdown -- > without it, some mahcines would reboot instead of shutting down! > Arguably this may have been an ACPI or BIOS bug rather than EHCI, but > nevertheless, the fix worked. See > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8903795a5275e0366acf961190c57074ad27f9bb > > and > > http://bugzilla.kernel.org/show_bug.cgi?id=7828
Ah, I see why you would want to turn off remote wakeup on those ports. However, I don't see that function actually does what the comment says. AFAIK, writing 1 to the registers represented by PORT_RWC_BITS only clears the port status bits related to current port events. It doesn't stop new events from being interpreted as remote wakeup events in the future. You would have to clear the PORT_WK* bits to turn off remote wakeup for a port. Am I misreading something? It doesn't matter much, since the fix worked, but it was very confusing to compare the ehci_turn_off_all_ports() and ehci_port_power(). Sarah - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
