Hi, I've recently get a macbook pro and I'm running a Fedora 22 (kernel 4.0.8-300.fc22.x86_64) on it. I'm looking to improve the power consumption, and I've found that applesmc continuously use 5% of CPU (and a bit less than a 1W). After investigation, it seems that the problem come from the motion sensor polling (at 50 ms interval) (see applesmc_idev_poll function) The sensor functionality is primarily intend to detect laptop fall and shutdown HDD before the shock. Matthew Garret sent a patch in 2011 (http://thread.gmane.org/gmane.linux.drivers.sensors/26911/focus=26960) to use interrupt to get free fall/high acceleration/shock information. This patch has been rejected cause a lack of use case for them. Shutting down the HDD could be a use case. This is already in use through /dev/freefall. (see Documentation/laptops/freefall.c for use case and drivers/platform/x86/dell-smo8800.c for a implementation) I understand that we may need polling the device to get motion input, but I don't use motion in user space and I prefer not using my CPU for nothing. Maybe it would be useful to separate the motion sensor code in a different module (or using a dynamic configuration) to be able to have this functionality only when we want it. I'm ready to make patches to add /dev/freefall handling base on Matthew Garret patch and move sensor detection to another module (or make it deactivable). But I would like to see with you before if you are ok with my proposition. Regards, Matthieu Gautier. PS, I'm pretty (totally) new into kernel patching. I understand quickly but you may have to explain longer :)
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