linux-kernel - Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGa+x85vxX8dbmk-8mOEQ03q6Ud1a-OfnV7t5-rNtu06vn_cSQ@mail.gmail.com>
Date:	Thu, 12 Sep 2013 14:40:15 -0700
From:	Kevin Hilman <khilman@...aro.org>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	linux-i2c@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-acpi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Lv Zheng <lv.zheng@...el.com>, Aaron Lu <aaron.lu@...el.com>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Mark Brown <broonie@...nel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client devices

On Thu, Sep 12, 2013 at 2:34 PM, Kevin Hilman <khilman@...aro.org> wrote:
> Mika Westerberg <mika.westerberg@...ux.intel.com> writes:
>
>> From: Aaron Lu <aaron.lu@...el.com>
>>
>> This patch adds runtime PM support for the I2C bus in a similar way that
>> has been done for PCI bus already. This means that the I2C bus core
>> prepares runtime PM for a client device just before a driver is about to be
>> bound to it. Devices that are not bound to any driver are not prepared for
>> runtime PM.
>>
>> In order to take advantage of this runtime PM support, the client device
>> driver needs drop the device runtime PM reference count by calling
>> pm_runtime_put() in its ->probe() callback and possibly implement rest of
>> the runtime PM callbacks.
>>
>> If the driver doesn't support runtime PM (like most of the existing I2C
>> client drivers), the device in question is regarded as being runtime PM
>> active and powered on.
>
> But for existing drivers which already support runtime PM (at least 7 by
> a quick grep), they will be stuck runtime enabled and stop hitting
> low-power states after this patch.

Oops, nevermind.  I was mixing this up with runtime PM on the i2c
adapter but this is for the i2c client.

Sorry for the noise.

Kevin
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/