From: Andrey Smirnov <andrew.smirnov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Alexandre Belloni
<alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
Cc: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org,
Alessandro Zummo
<a.zummo-BfzFCNDTiLLj+vYz1yj4TQ@public.gmane.org>,
Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>,
Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
Ian Campbell
<ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>,
Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 03/13] RTC: ds1307: Add DS1341 specific power-saving options
Date: Tue, 21 Jun 2016 19:34:56 -0700 [thread overview]
Message-ID: <CAHQ1cqGRqhOAqfJZEixkxAHZ4Y8dd-hD__T1ci0LS28Orphs3Q@mail.gmail.com> (raw)
In-Reply-To: <20160621210739.GY5809-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
On Tue, Jun 21, 2016 at 2:07 PM, Alexandre Belloni
<alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> 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
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next prev parent reply other threads:[~2016-06-22 2:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1465970379-14703-1-git-send-email-andrew.smirnov@gmail.com>
[not found] ` <1465970379-14703-1-git-send-email-andrew.smirnov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-06-15 5:59 ` [PATCH 03/13] RTC: ds1307: Add DS1341 specific power-saving options Andrey Smirnov
[not found] ` <1465970379-14703-4-git-send-email-andrew.smirnov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-06-19 14:29 ` Rob Herring
2016-06-19 18:12 ` Andrey Smirnov
[not found] ` <CAHQ1cqFfFpLmMMr9itinha9rotG7Btr9UmWbO2_0VWxX_HeG1g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-06-21 20:49 ` Rob Herring
2016-06-21 21:07 ` Alexandre Belloni
[not found] ` <20160621210739.GY5809-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
2016-06-22 2:34 ` Andrey Smirnov [this message]
[not found] ` <CAHQ1cqGRqhOAqfJZEixkxAHZ4Y8dd-hD__T1ci0LS28Orphs3Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-07-12 16:21 ` Andrey Smirnov
2016-07-19 22:47 ` Alexandre Belloni
[not found] ` <20160719224728.GP7132-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
2016-07-19 23:56 ` Andrey Smirnov
2016-07-20 9:02 ` Alexandre Belloni
[not found] ` <20160720090220.GQ7132-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
2016-07-20 14:36 ` Andrey Smirnov
[not found] ` <CAHQ1cqEoN7PEQApHBo-FOqumtLJWoURHOPZfrzL=6h2p4S0Fdg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-07-20 15:38 ` Alexandre Belloni
[not found] ` <20160720153836.GS7132-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
2016-07-20 16:11 ` Andrey Smirnov
2016-06-21 23:23 ` Andrey Smirnov
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