On Monday, September 07, 2015 11:42:41 PM Irina Tirdea wrote: > Add new option to sysfs control interface, allowing the user to force > suspend the device. Had we thought this had been a good idea, we'd have added that thing to the interface from the start. The problem with it is that user space generally doesn't know when it is safe to suspend a device, so it cannot force anything into runtime suspend. > This is useful for devices that need to be > suspended when closing the lid of a laptop or the screen of a mobile > device, while userspace still holds open handles to it and the > system does not enter system suspend. > > Add the "off" option to the sysfs control power interface, along with > the already present "on" and "auto". When this attribute is set to > "off", the device will be force suspended by calling its runtime > suspend callback and disabling runtime power management so that > further acceses to the device will not change the actual state. And how is user space supposed to know that it doesn't break things this way? > The device can be resumed by setting the attribute to "on" or "auto". > The behaviour of the interface when switching only between "on" > and "auto" states remains unchanged. > > Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx> > --- > > Hi, > > This is a proposal for suspending devices when the closing the lid of > a laptop or the screen of a mobile device. > > I am testing this with a Goodix touchscreen [1] for an Android mobile > device. Android has an userspace layer (power HAL) that would normally > close the touchscreen when the screen is closed. Android touchscreen > drivers usually provide a custom sysfs interface to allow this. > This would be better implemented in a common place, to avoid code > duplication and to simplify the driver code (as previosly discussed > in [1]). > > I know there are more ways to implement this, so I would appreciate > your feedback. So the feedback is that this is not going to work in general. Please use a different approach. Thanks, Rafael -- 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
