From: Pavel Machek <pavel@ucw.cz>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>,
yoma sophian <sophian.yoma@gmail.com>,
linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org
Subject: Re: how to enable suspend to ram for arm-64 bits
Date: Thu, 3 Nov 2016 10:57:58 +0100 [thread overview]
Message-ID: <20161103095758.GA7973@amd> (raw)
In-Reply-To: <20161019131145.GA11036@leverpostej>
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On Wed 2016-10-19 14:11:45, Mark Rutland wrote:
> On Wed, Oct 19, 2016 at 11:42:27AM +0200, Pavel Machek wrote:
> > On Tue 2016-10-18 11:45:39, Mark Rutland wrote:
>
> > Either the lowlevel suspend code is stable and bug free, and then
> > having that code is not a problem.
>
> This ignores the cost of maintaining that code. Kernel APIs change over
> time, and no code is ever completely stable, even if at one point in
> time it happens to be bug-free.
Well, kernel interfaces only change when there's good reason for a
change, and if you force stable binary interface to external
component, and there _is_ need for a change, we are all screwed.
> > BSD is better than closed source, but it also means that you will not
> > get the sources from your hw vendor.
>
> That depends on your hardware vendor, as always. There are a number of
> platform ports in the upstream ATF repo.
>
> It's also worth considering that a number of 32-bit arm parts require
> closed firmware (as far as I can tell, including the N900).
Yeah, but we are trying to remove closed firmware. Don't make people
add more of it...
> > Being separate module means it will be hard to debug, in area where
> > debugging is already pretty hard.
>
> It can be harder, yes. There are also benefits, given the same code can
> be tested on a variety of platforms.
What benefits? You are able to share code between platforms in kernel,
too.
> > Can it do advanced stuff like deep powersaving on N900 idle?
>
> Sorry, I don't know precisely what you're referring to.
>
> It can do things like shutting down entire CPU clusters (and IIRC
> associated interconnect) when all relevant CPUs are idle, if that's what
> you mean.
I mean equivalent power savings between idle system and system in
s2ram.
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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WARNING: multiple messages have this Message-ID (diff)
From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: how to enable suspend to ram for arm-64 bits
Date: Thu, 3 Nov 2016 10:57:58 +0100 [thread overview]
Message-ID: <20161103095758.GA7973@amd> (raw)
In-Reply-To: <20161019131145.GA11036@leverpostej>
On Wed 2016-10-19 14:11:45, Mark Rutland wrote:
> On Wed, Oct 19, 2016 at 11:42:27AM +0200, Pavel Machek wrote:
> > On Tue 2016-10-18 11:45:39, Mark Rutland wrote:
>
> > Either the lowlevel suspend code is stable and bug free, and then
> > having that code is not a problem.
>
> This ignores the cost of maintaining that code. Kernel APIs change over
> time, and no code is ever completely stable, even if at one point in
> time it happens to be bug-free.
Well, kernel interfaces only change when there's good reason for a
change, and if you force stable binary interface to external
component, and there _is_ need for a change, we are all screwed.
> > BSD is better than closed source, but it also means that you will not
> > get the sources from your hw vendor.
>
> That depends on your hardware vendor, as always. There are a number of
> platform ports in the upstream ATF repo.
>
> It's also worth considering that a number of 32-bit arm parts require
> closed firmware (as far as I can tell, including the N900).
Yeah, but we are trying to remove closed firmware. Don't make people
add more of it...
> > Being separate module means it will be hard to debug, in area where
> > debugging is already pretty hard.
>
> It can be harder, yes. There are also benefits, given the same code can
> be tested on a variety of platforms.
What benefits? You are able to share code between platforms in kernel,
too.
> > Can it do advanced stuff like deep powersaving on N900 idle?
>
> Sorry, I don't know precisely what you're referring to.
>
> It can do things like shutting down entire CPU clusters (and IIRC
> associated interconnect) when all relevant CPUs are idle, if that's what
> you mean.
I mean equivalent power savings between idle system and system in
s2ram.
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2016-11-03 9:58 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-17 17:26 how to enable suspend to ram for arm-64 bits yoma sophian
2016-08-17 17:26 ` yoma sophian
2016-08-17 17:49 ` Sudeep Holla
2016-08-17 17:49 ` Sudeep Holla
2016-08-18 2:07 ` yoma sophian
2016-08-18 2:07 ` yoma sophian
2016-08-18 8:47 ` Sudeep Holla
2016-08-18 8:47 ` Sudeep Holla
2016-08-18 10:43 ` yoma sophian
2016-08-18 10:43 ` yoma sophian
2016-08-18 10:52 ` Sudeep Holla
2016-08-18 10:52 ` Sudeep Holla
2016-08-22 14:41 ` yoma sophian
2016-08-22 14:41 ` yoma sophian
2016-08-22 15:00 ` Sudeep Holla
2016-08-22 15:00 ` Sudeep Holla
2016-10-18 10:00 ` Pavel Machek
2016-10-18 10:00 ` Pavel Machek
2016-10-18 10:21 ` Sudeep Holla
2016-10-18 10:21 ` Sudeep Holla
2016-10-18 10:28 ` Lorenzo Pieralisi
2016-10-18 10:28 ` Lorenzo Pieralisi
2016-10-18 10:45 ` Mark Rutland
2016-10-18 10:45 ` Mark Rutland
2016-10-18 10:59 ` Sudeep Holla
2016-10-18 10:59 ` Sudeep Holla
2016-10-19 7:18 ` yoma sophian
2016-10-19 7:18 ` yoma sophian
2016-10-19 9:42 ` Pavel Machek
2016-10-19 9:42 ` Pavel Machek
2016-10-19 13:11 ` Mark Rutland
2016-10-19 13:11 ` Mark Rutland
2016-11-03 9:57 ` Pavel Machek [this message]
2016-11-03 9:57 ` Pavel Machek
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