On Mon, 2015-09-21 at 16:02 -0400, Alan Stern wrote: > On Mon, 21 Sep 2015, Dmitry Torokhov wrote: > > > > What happens if the "inhibit" control is turned on and the driver puts > > > the device into runtime suspend, but then an I/O request arrives? > > > > > > If the I/O request originated from userspace, it means the > > > user is violating the terms of the "inhibit" control. Should > > > the request simply fail? > > > > What user? User that inhibited it or user that tried to use the device? > > Normally they would be the same. But even if they aren't, someone has > violated the kernel interface: The first user told the kernel a > particular device wasn't going to be used, and then the second user > tried to use it. If we assume that user space speaks with a uniform voice on that issue, it can just as well close the device. It seems to me that declaring a device idle is a privileged operation. > Of course, this issue doesn't arise for devices that merely report > external events. Indeed. We can handle output to suspended devices by waking them. I don't see why this case is different. We are talking about input only. > The runtime-PM "usage" value for these devices is a little tricky to > calculate. It should be nonzero if there are any open files _and_ the > device isn't "inhibited". I don't know the best way to represent that > kind of condition in the runtime PM framework. Does that make sense in the generic framework at all? I still think that drivers should cease IO for input in such cases. That should involve a common callback, but no counter. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
