From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/4] pinctrl: Add support for additional dynamic states
Date: Thu, 18 Jul 2013 13:26:56 -0600 [thread overview]
Message-ID: <51E84180.6080902@wwwdotorg.org> (raw)
In-Reply-To: <20130718073638.GP7656@atomide.com>
On 07/18/2013 01:36 AM, Tony Lindgren wrote:
> * Stephen Warren <swarren@wwwdotorg•org> [130717 14:30]:
>> On 07/16/2013 03:05 AM, Tony Lindgren wrote:
...
>> Why shouldn't e.g. a pinctrl-based I2C mux also be able to do runtime
>> PM? Does the mux setting select which states are used for runtime PM, or
>> does runtime PM override the basic mux setting, or must the pincrl-I2C
>> mux manually implement custom runtime-PM/pinctrl interaction since
>> there's no generic answer to those questions? How many more custom
>> exceptions will there be?
>
> The idea is that runtime PM will never touch the basic mux settings
> at all. The "default" state should be considered a static state
> that is claimed during driver probe, and released when the driver
> is unloaded. This is typically let's say 90% of the pins for any
> device.
>
> For runtime PM, we can just toggle the PM related pinctrl states as
> they have been verified to match the active state during init.
>
> So I don't see why pinctrl-I2C would have to do anything specific.
> All that is required is that the pins are grouped for the consumer
> driver, and we can provide some automated checks on the states for
> runtime PM.
So, consider a pinctrl-based I2C mux. It has 2 states to cover two I2C
buses:
a) bus 1: I2C controller is muxed out onto one set of pins.
b) bus 2: I2C controller is muxed out onto another set of pins.
Now, the system could go idle in either of those 2 states, and then
later need to return to one of those states. I just don't see how that
would work, since the runtime PM code in this series switches to *an*
active state when the device becomes non-idle. If the definition of the
idle state switches the mux function for both sets of pins to some
idle/quiescent value, then you'd need to do different reprogramming when
going back to "the" active state; I guess the system would need to
remember which state was active before switching to idle, then switch
back to that same state rather than hard-coding the active state name as
"active"...
next prev parent reply other threads:[~2013-07-18 19:26 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-16 9:05 [PATCH 0/4] improved support for runtime muxing for pinctrl Tony Lindgren
2013-07-16 9:05 ` [PATCH 1/4] pinctrl: Remove duplicate code in pinctrl_pm_select_state functions Tony Lindgren
2013-07-16 13:15 ` Grygorii Strashko
2013-07-16 13:41 ` Tony Lindgren
2013-07-16 14:25 ` Grygorii Strashko
2013-07-17 6:31 ` Tony Lindgren
2013-07-16 9:05 ` [PATCH 2/4] pinctrl: Allow pinctrl to have multiple active states Tony Lindgren
2013-07-17 20:55 ` Stephen Warren
2013-07-16 9:05 ` [PATCH 3/4] pinctrl: Add support for additional dynamic states Tony Lindgren
2013-07-16 9:35 ` Felipe Balbi
2013-07-16 12:06 ` Tony Lindgren
2013-07-17 21:14 ` Stephen Warren
2013-07-18 7:25 ` Tony Lindgren
2013-07-18 10:53 ` Tony Lindgren
2013-07-18 19:21 ` Stephen Warren
2013-07-19 7:29 ` Tony Lindgren
2013-07-19 18:52 ` Stephen Warren
2013-07-29 9:05 ` Tony Lindgren
2013-07-29 22:01 ` Stephen Warren
2013-08-14 16:41 ` Linus Walleij
2013-07-17 21:23 ` Stephen Warren
2013-07-18 7:36 ` Tony Lindgren
2013-07-18 19:26 ` Stephen Warren [this message]
2013-07-19 7:39 ` Tony Lindgren
2013-07-19 10:29 ` Grygorii Strashko
2013-07-19 19:03 ` Stephen Warren
2013-07-22 23:15 ` Linus Walleij
2013-07-29 9:08 ` Tony Lindgren
2013-07-19 18:58 ` Stephen Warren
2013-07-29 9:21 ` Tony Lindgren
2013-07-29 22:08 ` Stephen Warren
2013-07-22 23:07 ` Linus Walleij
2013-07-29 9:31 ` Tony Lindgren
2013-07-16 9:05 ` [PATCH 4/4] drivers: Add pinctrl handling for dynamic pin states Tony Lindgren
2013-07-17 21:21 ` Stephen Warren
2013-07-18 7:50 ` Tony Lindgren
2013-07-18 13:48 ` Tony Lindgren
2013-07-16 9:14 ` [PATCH 0/4] improved support for runtime muxing for pinctrl Tony Lindgren
2013-07-17 11:49 ` Grygorii Strashko
-- strict thread matches above, loose matches on Subject: below --
2013-07-18 15:15 [PATCHv2 " Tony Lindgren
2013-07-18 15:15 ` [PATCH 3/4] pinctrl: Add support for additional dynamic states Tony Lindgren
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