From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Sakari Ailus <sakari.ailus@iki.fi>, Arnd Bergmann <arnd@arndb.de>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
linux-media@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH 1/1] smiapp: Implement power-on and power-off sequences without runtime PM
Date: Fri, 25 Nov 2016 21:34:56 +0200 [thread overview]
Message-ID: <3007760.0ebxS8fqmr@avalon> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1611251014130.1509-100000@netrider.rowland.org>
Hi Alan,
On Friday 25 Nov 2016 10:21:21 Alan Stern wrote:
> On Fri, 25 Nov 2016, Sakari Ailus wrote:
> > On Thu, Nov 24, 2016 at 09:15:39PM -0500, Alan Stern wrote:
> >> On Fri, 25 Nov 2016, Laurent Pinchart wrote:
> >>> Dear linux-pm developers, what's the suggested way to ensure that a
> >>> runtime- pm-enabled driver can run fine on a system with CONFIG_PM
> >>> disabled ?
> >>
> >> The exact point of your question isn't entirely clear. In the most
> >> literal sense, the best ways to ensure this are (1) audit the code, and
> >> (2) actually try it.
> >>
> >> I have a feeling this doesn't quite answer your question, however. :-)
> >
> > The question is related to devices that require certain power-up and
> > power-down sequences that are now implemented as PM runtime hooks that,
> > without CONFIG_PM defined, will not be executed. Is there a better way
> > than to handle this than have an implementation in the driver for the PM
> > runtime and non-PM runtime case separately?
>
> Yes, there is a better way. For the initial power-up and final
> power-down sequences, don't rely on the PM core to invoke the
> callbacks. Just call them directly, yourself.
>
> For example, as part of the probe routine, instead of doing this:
>
> pm_runtime_set_suspended(dev);
> pm_runtime_enable(dev);
> pm_runtime_get_sync(dev);
>
> Do this:
>
> pm_runtime_set_active(dev);
> pm_runtime_get_noresume(dev);
> pm_runtime_enable(dev);
> /*
> * In case CONFIG_PM is disabled, invoke the runtime-resume
> * callback directly.
> */
> my_runtime_resume(dev);
Wouldn't it be cleaner for drivers not to have to handle this manually (which
gives an opportunity to get it wrong) but instead have pm_runtime_enable()
call the runtime resume callback when CONFIG_PM is disabled ?
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2016-11-25 19:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-18 13:50 [PATCH 1/1] smiapp: Implement power-on and power-off sequences without runtime PM Sakari Ailus
2016-11-18 16:09 ` Arnd Bergmann
2016-11-22 18:31 ` Laurent Pinchart
2016-11-22 20:58 ` Arnd Bergmann
2016-11-25 0:43 ` Laurent Pinchart
2016-11-25 2:15 ` Alan Stern
2016-11-25 2:15 ` Alan Stern
2016-11-25 7:48 ` Sakari Ailus
2016-11-25 15:21 ` Alan Stern
2016-11-25 15:21 ` Alan Stern
2016-11-25 19:34 ` Laurent Pinchart [this message]
2016-11-26 20:10 ` Alan Stern
2016-11-26 20:10 ` Alan Stern
2016-11-28 7:58 ` Laurent Pinchart
2016-11-28 15:45 ` Alan Stern
2016-11-28 15:45 ` Alan Stern
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