On Thu, Dec 20, 2012 at 08:55:33PM -0800, Greg KH wrote: > On Fri, Dec 21, 2012 at 12:28:38PM +0800, Peter Chen wrote: > > On Tue, Dec 18, 2012 at 11:11:15AM -0500, Alan Stern wrote: > > > I suggest that we remove the CONFIG_USB_SUSPEND option, starting in > > > 3.9. Practically everyone enables it, and the amount of code it > > > protects is fairly small (just portions of usbcore, nothing in the > > > drivers). > > > > > > Basically, if people don't want their kernels to save power then they > > > should turn off CONFIG_PM. > > > > > > Objections, anyone? > > Sorry, I may not agree with this due to below reasons: > > > > - Some customers wants system PM, but do not want usb runtime power > > management, such as Car Navigation System. They want system > > responds fast after user press power on key, but they don't care > > usb power during runtime. > > What is "fast"? And you can always explicitly keep the device away by > writing to the proper sysfs file, right? I mean system suspend/resume. > > And this isn't always true from all automotive systems, some that I talk > to in that industry do need this, as they are not allowed to drain a lot > of power all the time (think about when running on a car battery), and > their power budget is quite low. Correct, CONFIG_USB_SUSPEND can let the user choose if they want USB runtime PM or not, you know different users may have different requirements. > > > - For embedded system, we have may SoCs, and USB low power mode > > is the most challenge job when we bring up new USB module, usually, > > our develop sequence like: basic USB functions --> USB function after > > System suspend/resume --> USB Runtime PM. We usually disable USB > > runtime PM at first. > > So you need to get this working properly for your devices, what's wrong > with that? :) Yes, we can debug that but it needs some efforts. Maybe for alpha release we only add basic USB function, for beta release we will add usb suspend/resume function. Then, at next release, we will add USB runtime PM. I just want to say keep CONFIG_USB_SUSPEND can give users more choices no matter debug, development or final product procedure. -- Best Regards, Peter Chen -- 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
