On 20 May 2015 14:44 Rob Herring wrote: > To: Opensource [Steve Twiss] > Cc: Ian Campbell; Kumar Gala; Lee Jones; Mark Rutland; Pawel Moll; Rob > Herring; DT; David Dajun Chen; Dmitry Torokhov; INPUT; LKML; Samuel Ortiz; > Support Opensource > Subject: Re: [RESEND PATCH V4 2/3] devicetree: Add bindings for DA9063 > OnKey > > On Tue, May 19, 2015 at 5:32 AM, S Twiss > <stwiss.opensource@xxxxxxxxxxx> wrote: > > From: Steve Twiss <stwiss.opensource@xxxxxxxxxxx> > > > > Add device tree bindings for the DA9063 OnKey driver > > > > Acked-by: Lee Jones <lee.jones@xxxxxxxxxx> > > Hi Rob, Thanks for the Ack. > I would think a long key press would be a h/w powerdown rather than a > key event as how do you poweroff/reset a hung system? That doesn't > really affect the binding though, so: yep.. That H/W controlled shutdown is not covered in the device driver because it is defaulted by the hardware PMIC. The DA9063 OnKey has are four modes of operation -- and one of them is a H/W controlled shutdown (to reset a hung system). Holding down the OnKey for a "long-long" key-press, if there is no software intervention, then the PMIC will chop the power. The other three modes are ... (a) Short key press (b) Long-key press (c) Long-long key press These modes *are* handled by the S/W driver. (a) The short key-press being the usual sleep/suspend. (b) Long key press is the KEY_POWER (bringing up a dialog on Android to ask if the user wants to shutdown the device) -- this is the one that can be disabled by the device tree binding. (c) Long-long key press -- this is the software equivalent to the H/W shutdown for a hung system. Instead of the hardware pulling the plug, the software sends a command to tell the PMIC to pull the plug. If that last one sounds like a repeat of the H/W shutdown, then that is because it almost is. It covers the use case when the user decides to shutdown their device by doing a long-long key press. The difference here is that the software is still able to respond, and so there is space for any important house-keeping (say to save important data) before the software sends a command to tell the PMIC to pull the plug. The fail-safe at this point is: if the S/W really isn't responding, then the hardware monitors the long-long key-press and if there is no intervention by software, the PMIC pulls the power plug 1 second later. Regards, Steve ��.n��������+%������w��{.n����z�{��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f