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.
next prev parent 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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