From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Date: Tue, 20 Oct 2015 16:21:55 +0000
Subject: Re: [GIT PULL] On-demand device probing
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To: Alan Stern <stern@rowland.harvard.edu>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh@kernel.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, David Woodhouse <dwmw2@infradead.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Russell King <linux@arm.linux.org.uk>, Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@codeaurora.org>, Vinod Koul <vinod.koul@intel.com>, Dan Williams <dan.j.williams@intel.com>, Linus Walleij <linus.walleij@linaro.org>, Alexandre Courbot <gnurou@gmail.com>, Thierry Reding <thierry.reding@gmail.com>, David Airlie <airlied@linux.ie>, =?UTF-8?Q?Terje_Bergstr=C3=B6m?= <tbergstrom@nvidia.com>, Stephen Warren <swarren@wwwdotorg.org>, Wolfram Sang <wsa@the-dreams.de>, Frank Rowand <frowand.list@gmail.com>, Grant Likely <grant.likely@linaro.org>, Kishon Vijay Abraham I <kishon@ti.com>, Sebastian Reichel <sre@kernel.org>, Dmitry Eremin-Solenikov <dbaryshkov@gmail.c>

On 20 October 2015 at 18:04, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Tue, 20 Oct 2015, Mark Brown wrote:
>
>> On Tue, Oct 20, 2015 at 10:40:03AM -0400, Alan Stern wrote:
>>
>> > Furthermore, that applies only to devices that use synchronous suspend.
>> > Async suspend is becoming common, and there the only restrictions are
>> > parent-child relations plus whatever explicit requirements that drivers
>> > impose by calling device_pm_wait_for_dev().
>>
>> Hrm, this is the first I'd noticed that feature though I see the initial
>> commit dates from January.
>
> Async suspend and device_pm_wait_for_dev() were added in January 2010,
> not 2015!
>
>>  It looks like most of the users are PCs at
>> the minute but we should be using it more widely for embedded things,
>> there's definitely some cases I'm aware of where it will allow us to
>> remove some open coding.
>>
>> It does seem like we want to be feeding dependency information we
>> discover for probing way into the suspend dependencies...
>
> Rafael has been thinking about a way to do this systematically.
> Nothing concrete has emerged yet.

This iteration of the series would make this quite easy, as
dependencies are calculated before probes are attempted:

https://lkml.org/lkml/2015/6/17/311

Regards,

Tomeu

> Alan Stern
>
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