From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Smirnov Subject: Re: [PATCH 03/13] RTC: ds1307: Add DS1341 specific power-saving options Date: Tue, 21 Jun 2016 19:34:56 -0700 Message-ID: References: <1465970379-14703-1-git-send-email-andrew.smirnov@gmail.com> <1465970379-14703-4-git-send-email-andrew.smirnov@gmail.com> <20160619142934.GA8522@rob-hp-laptop> <20160621204904.GA9779@rob-hp-laptop> <20160621210739.GY5809@piout.net> Reply-To: rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Sender: rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org In-Reply-To: <20160621210739.GY5809-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Alexandre Belloni Cc: Rob Herring , rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Alessandro Zummo , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Tue, Jun 21, 2016 at 2:07 PM, Alexandre Belloni wrote: > On 21/06/2016 at 15:49:04 -0500, Rob Herring wrote : >> So wouldn't you want to set one mode while running and the lower power >> mode while suspended? I'm trying to understand the frequency of changing >> this. If it is always one setting for a board, then yes it belongs in >> DT. If it is a user decision, then it probably shouldn't be in DT. >> >> Seeing as these are reused, I've probably already had this discussion... >> > > I would agree with Rob here. It may be better to provide a sysfs > interface to configure that particular behavior. I don't see any value in doing that, could you give me a realistic example of a scenario in which a user would want to spend some of uptime with RTC oscillator fault detection/glitch filtering disabled and then enable it? > This is usually ok because the use case is: > - the RTC is not configured, time has never been set > - time is set for the first time > - the user can set the oscillator mode/detection/... Unfortunately exposing that feature using sysfs gives you a leaky abstraction and your userspace instead of using a generic RTC starts using DS1341 RTC. So to accommodate for that a user would have to: a) Write + integrate a userspace tool to set the mode (which IMHO is decided upon once and doesn't change) b) If a board design is new and there's a chance of moving this chip to a different I2C bus, the code above would have to account for that and not hardcore sysfs path c) If board's BSP is intended to be used in multiple generations of a product, not all of which would use DS1341, it would be necessary to accommodate for that by either more code in the tool or an additional BSP build configuration variant > - on subsequent reboots, the mode is kept alongside the time and date > This assumes that your bootloader leaves those mode bits alone. > I would advise against trying to set a mode automatically in the driver > because you may have unexpected power cuts and it may then let the RTC > consume more power than what you really want. > I fell like I am not understanding you correctly. Why would moving configuration decision logic into userspace improve the situation in case of unexpected power loss? Andrey -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout.