On Thu, Jun 21, 2012 at 05:08:58PM -0700, Sarah Sharp wrote: > On Thu, Jun 21, 2012 at 12:31:12PM -0500, Alexis Cortes wrote: > > Hi Greg, > > > > I understand your concerns, however as I mentioned before, any xHCI host > > that has this particular re-driver between its root-ports and the physical > > ports of the system will be subject to suffer of this compliance mode issue > > (once the port has entered compliance mode, it becomes unusable so no device > > that is plugged to that port will work until a warm reset is applied to it). > > For a system that has this re-driver, this problem could hit about 20%-40% > > of the times (however this percentage is subject to the quality of the > > internal connection) and unfortunately there is no way to programmatically > > detect if this re-driver is on the system. > > > > As Sarah proposed, we certainly can apply this patch as a module parameter > > disabled by default and let know our clients that we know are using this > > re-driver to enable the feature to avoid the issue. > > I don't think that would work very well. Are those clients supposed to > notify Linux OSVs when a system will ship with that redriver so they can > turn it on for Linux preloads of those systems? What about the average > Linux user who installs Linux themselves? > > An alternative approach, since you know which clients are using the > re-driver, is to just add a quirk, and get them to tell us when they're > shipping a system with your redriver. Then we can turn it on in the > mainline kernel, all Linux distros will pick it up, and we will avoid > disgruntled users. > > Or we can just modify the timer to a more reasonable value like 10 > seconds, and users will just have to put up with the longer enumeration > times. > > Greg, what about exporting a sysfs file to change the polling interval? > We could run the timer every 2 seconds by default, but get powertop to > add a new setting for turning the interval off. Ick, a sysfs file is almost as bad as a kernel module option, how are you going to tell users / distros when to turn it off or not if you don't know if it is needed or not? We really need a way to determine the hardware here. Alexis, what are you doing on Windows for this? Surely you can't be turning a timer on every 2 seconds for all Windows systems in the world, are you? thanks, greg k-h -- 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
