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From: Alex Courbot <acourbot@nvidia.com>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>,
	Stephen Warren <swarren@nvidia.com>,
	Thierry Reding <thierry.reding@avionic-design.de>,
	Mark Zhang <markz@nvidia.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	Rob Herring <rob.herring@calxeda.com>,
	Mark Brown <broonie@opensource.wolfsonmicro.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>,
	"devicetree-discuss@lists.ozlabs.org" 
	<devicetree-discuss@lists.ozlabs.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	Alexandre Courbot <gnurou@gmail.com>
Subject: Re: [PATCHv9 1/3] Runtime Interpreted Power Sequences
Date: Wed, 21 Nov 2012 10:56:36 +0900	[thread overview]
Message-ID: <4316169.5QXVzv7peZ@percival> (raw)
In-Reply-To: <50AB9832.90709@ti.com>

Hi Tomi,

On Tuesday 20 November 2012 22:48:18 Tomi Valkeinen wrote:
> I guess there's a reason, but the above looks a bit inconsistent. For
> gpio you define the gpio resource inside the step. For power and pwm the
> resource is defined before the steps. Why wouldn't "pwm = <&pwm 2
> 5000000>;" work in step2?

That's mostly a framework issue. Most frameworks do not export a function that 
allow to dereference a phandle - they expect resources to be declared right 
under the device node and accessed by name through foo_get(device, name). So 
using phandles in power sequences would require to export these additional 
functions and also opens the door to some inconsistencies - for instance, your 
PWM phandle could be referenced a second time in the sequence with a different 
period - how do you know that these are actually referring the same PWM 
device?

> > +When a power sequence is run, its steps is executed one after the other
> > until +one step fails or the end of the sequence is reached.
> 
> The document doesn't give any hint of what the driver should do if
> running the power sequence fails. Run the "opposite" power sequence?
> Will that work for all resources? I'm mainly thinking of a case where
> each enable of the resource should be matched by a disable, i.e. you
> can't call disable if no enable was called.

We discussed that issue already (around v5 I think) and the conclusion was 
that it should be up to the driver. When we simply enable/disable resources it 
is easy to revert, but in the future non-boolean properties will likely be 
introduced, and these cannot easily be reverted. Moreover some drivers might 
have more complex recovery needs. This deserves more discussion I think, as 
I'd like to have some "generic" recovery mechanism that covers most of the 
cases.

Alex.


  reply	other threads:[~2012-11-21  1:56 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-17 10:55 [PATCHv9 0/3] Runtime Interpreted Power Sequences Alexandre Courbot
2012-11-17 10:55 ` [PATCHv9 1/3] " Alexandre Courbot
2012-11-17 11:38   ` Anton Vorontsov
2012-11-19  2:29     ` Alex Courbot
2012-11-19  2:32       ` Anton Vorontsov
2012-11-20 14:48   ` Tomi Valkeinen
2012-11-21  1:56     ` Alex Courbot [this message]
2012-11-21  8:13       ` Tomi Valkeinen
2012-11-21  8:32         ` Alex Courbot
2012-11-21  8:48           ` Tomi Valkeinen
2012-11-21 10:00             ` Alex Courbot
2012-11-22 13:01               ` Grant Likely
2012-11-20 21:54   ` Grant Likely
2012-11-21  1:31     ` Mark Brown
2012-11-21 16:44       ` Grant Likely
2012-11-22  8:57       ` Linus Walleij
2012-11-22  9:55         ` Alexandre Courbot
2012-11-23  1:44         ` Mark Brown
2012-11-21  4:23     ` Alex Courbot
2012-11-21 11:06       ` Tomi Valkeinen
2012-11-21 11:40         ` Thierry Reding
2012-11-21 12:04           ` Tomi Valkeinen
2012-11-21 13:00             ` Thierry Reding
2012-11-21 13:32               ` Tomi Valkeinen
2012-11-21 15:02                 ` Alexandre Courbot
2012-11-21 15:12                   ` Thierry Reding
2012-11-22  2:01                     ` Alexandre Courbot
2012-11-22  2:06                       ` Mark Brown
2012-11-22  3:09                         ` Alexandre Courbot
2012-11-22 13:39                     ` Grant Likely
2012-11-27 15:19               ` Laurent Pinchart
2012-11-27 15:08             ` Laurent Pinchart
2012-11-27 15:19               ` Tomi Valkeinen
2012-11-27 15:37                 ` Laurent Pinchart
2012-11-27 16:46                   ` Mark Brown
2012-11-27 14:47           ` Laurent Pinchart
2012-11-22 13:39       ` Grant Likely
2012-11-22 21:40         ` Thierry Reding
2012-11-26 11:49           ` Alex Courbot
2012-11-26 15:34           ` Grant Likely
2012-11-17 10:55 ` [PATCHv9 2/3] pwm_backlight: use power sequences Alexandre Courbot
2012-11-17 10:55 ` [PATCHv9 3/3] Take maintainership of " Alexandre Courbot
2012-11-20 21:58 ` [PATCHv9 0/3] Runtime Interpreted Power Sequences Grant Likely

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