On Thu, 1 Nov 2012, Greg KH wrote: > On Thu, Nov 01, 2012 at 08:59:11AM -0700, Sarah Sharp wrote: > > On Mon, Oct 29, 2012 at 04:28:39PM +0800, Lan Tianyu wrote: > > > This patch is to set xhci root hub's DeviceRemovable according to usb port's > > > connect type which currently comes from ACPI information. If ACPI information > > > was different with PORTSC, there would be a warning. > > > > You should also add the note here that you're trusting the ACPI tables > > over the xHCI DeviceRemovable port status register bits when you decide > > whether to mark a port as hard-wired. Tianyu is doing it this way > > because Windows is likely to rely on the ACPI tables over the > > DeviceRemovable bits. > > "Likely"? Is that going to be tested anywhere in the Windows test > suites? > > I would think that the bits would be more reliable than the ACPI tables. I would expect that the ACPI tables and other parts of the BIOS are easier for manufacturers to update than the settings in other system components (like xHCI controllers). Even an end user can re-flash the BIOS. Of course, that doesn't mean the ACPI values are always going to be right; firmware-derived values are notoriously unreliable. And as for which values Windows will rely upon, probably only the people in Redmond know for sure. Alan Stern -- 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
