On Friday, September 21, 2012, Peter Stuge wrote: > Sarah Sharp wrote: > > > > If userspace really wants the port off (e.g. to disconnect and > > > > reconnect a misbehaving device), then it can set the sysfs file > > > > to off. > > > > > > And unless all ganged ports are also off it will fail. Userspace will > > > want to know about that, and why, along with a reference that can be > > > matched against the list of ganged sets of ports. > > > > Ah, right. Yes, we should probably add some dmesg info lines about > > why we can't turn off a port right now. > > dmesg isn't very programmable. Maybe ioctl after all? Trust me that I > don't have a preference, it's just that I don't know how sysfs could > report back the relevant failure info in a race-free way. Well, we actually need to handle power domains appropriately. Unfortunately, ACPI doesn't support the power domain concept directly and tries to kind of hide them behind power resources, but let's face it, they are what they are. Some work in that direction has been done in the ARM space, where we have much more direct access to hardware, and I suppose it may be extended to things like "ganged sets of ports" (which actually are power domains). Thanks, Rafael -- 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
