From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [PATCH 1/3] dt-bindings: mfd: Document the RTC present on MAX77620 Date: Fri, 1 May 2020 15:53:09 +0200 Message-ID: <20200501135309.GC51277@piout.net> References: <20200417170825.2551367-1-thierry.reding@gmail.com> <20200430140701.GA21776@bogus> <20200430141520.GA101194@piout.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rob Herring Cc: Thierry Reding , Lee Jones , Alessandro Zummo , Jon Hunter , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" , linux-tegra , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On 01/05/2020 08:00:11-0500, Rob Herring wrote: > > I don't think this is true because in the case of a discrete RTC, its > > interrupt pin can be connected directly to a PMIC to power up a board > > instead of being connected to the SoC. In that case we don't have an > > interrupt property but the RTC is still a wakeup source. This is the > > usual use case for wakeup-source in the RTC subsystem. Else, if there is > > an interrupt, then we assume the RTC is a wakeup source and there is no > > need to have the wakeup-source property. > > Yes, that would be an example of "unless the wakeup mechanism is > somehow not an interrupt". I guess I should add not an interrupt from > the perspective of the OS. > > So if the wakeup is self contained within the PMIC, why do we need a > DT property? The capability is always there and enabling/disabling > wakeup from it is userspace policy. > Yes, for this particular case, I'm not sure wakeup-source is actually necessary. If the interrupt line is used to wakeup the SoC, then the presence of the interrupts property is enough to enable wakeup. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com