On Fri, May 27, 2011 at 09:19:05AM +0800, Greg KH wrote: > On Thu, May 26, 2011 at 04:45:38PM -0700, Sarah Sharp wrote: > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > index 7c6624e..67f2da2 100644 > > --- a/Documentation/kernel-parameters.txt > > +++ b/Documentation/kernel-parameters.txt > > @@ -2722,6 +2722,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > > the unplug protocol > > never -- do not unplug even if version check succeeds > > > > + xhci_switch_mask= [USB] > > + Format: bitmap of ports to switch over from EHCI to xHCI > > + during early boot and system resume from hibernate. > > + If this kernel parameter is set to zero and the xHCI > > + BIOS option is set to "disabled" or "auto", all ports > > + under the xHCI host controller on some Intel chipsets > > + will be disabled, and USB 3.0 devices will show up at > > + USB 2.0 speeds under the EHCI host controller. > > + > > Ick, no, I really don't want a new command line option for this. Can't > we handle this dynamically somehow? Otherwise the distros are all going > to have to add logic for this to their installer to change the kernel > command line and that will take forever to get implemented. > > Why wouldn't we just want this to work "properly" all the time on this > hardware and always use the ports in XHCI mode as we do have a working > driver for this, unlike other operating systems :) In theory, there shouldn't be any reason not to use the xHCI controller. The only thing I can think of is that the xHCI host can only handle powers of two intervals, but that shouldn't be a big deal. I'm quite happy to remove the command line option and just blindly do the switchover. I'll send an updated patch in after dinner. Sarah -- 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
