linux-kernel - Re: Nokia N900 retention mode in v4.6, camera buttons fun

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Date:	Sun, 1 May 2016 17:48:56 +0200
From:	Sebastian Reichel <sre@...nel.org>
To:	Pavel Machek <pavel@....cz>
Cc:	Pali Rohár <pali.rohar@...il.com>,
	Tony Lindgren <tony@...mide.com>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-omap@...r.kernel.org, khilman@...nel.org,
	aaro.koskinen@....fi, ivo.g.dimitrov.75@...il.com,
	patrikbachan@...il.com, serge@...lyn.com,
	Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: Nokia N900 retention mode in v4.6, camera buttons fun

Hi,

On Sun, May 01, 2016 at 10:52:36AM +0200, Pavel Machek wrote:
> On Fri 2016-04-29 22:06:00, Sebastian Reichel wrote:
> > On Thu, Apr 21, 2016 at 03:04:50PM +0200, Pali Rohár wrote:
> > > > CONFIG_HSI breaks power management completely, so power management
> > > > with modem will be another topic.  
> > > 
> > > Sebastian, any idea why power management does not work for HSI?
> > 
> > I wasn't aware, that pm_runtime_irq_safe() basically breaks runtime
> > PM until Tony's fix for musb (even though it's logical when thinking
> > about it). Currently omap-ssi and omap-ssi-port make use of
> > pm_runtime_irq_safe().
> > 
> > Since pm_runtime_get_sync/pm_runtime_put_sync is called from
> > tasklets in omap-ssi (and omap-ssi-port) it cannot be simply
> > removed. So fixing PM for the ssi controller requires reworking
> > the driver in a non trivial way.
> 
> I see latest series, and it also talks about frequency scaling. But I
> guess it is not going to fix this issue?

No, this is independent of the runtime PM problems. I also worked
on runtime PM/idling yesterday and pm_runtime_irq_safe is the main
culprit for breaking it (not the only one, though). It's not yet
finished though

-- Sebastian

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