Re: [RFC] ARM: OMAP2+: omap_device: add pinctrl handling

[Grygorii Strashko]

Picture format fixed. Sorry for that.

On 06/26/2013 04:20 PM, Grygorii Strashko wrote:
> Hi All,
>
> On 06/25/2013 09:58 AM, Tony Lindgren wrote:
> > * Linus Walleij <linus.walleij@xxxxxxxxxx> [130624 05:13]:
> > > On Fri, Jun 21, 2013 at 5:03 PM, Grygorii Strashko
> > > <grygorii.strashko@xxxxxx> wrote:
> > >
> > > > Hence, add pinctrl handling in omap_device core:
> > > > 1) on PM runtime resume
> > > > - switch pinctrl state to "default" (todo: "active")
> > > > 2) on PM runtime suspend
> > > > - switch pinctrl state to "idle"
> > > > 3) during system wide suspend
> > > > - switch pinctrl state to "sleep" or "idle" if omap_device core
> > > > disables device
> > > > - switch pinctrl state to "sleep" if device is disabled already
> > Do you need a separate setting for "idle" and "sleep", or are
> > they the same?
> >
> > > > 4) during system wide resume
> > > > - switch pinctrl state to "default" (todo: "active") if omap_device
> > > > core has
> > > >    disabled  device during suspend
> > > > - switch pinctrl state to "idle" if device was already disabled
> > > > before suspend
> > > I don't understand step 4.
> > >
> > > I get the creeps about whether the system is runtime suspended
> > > or runtime resumed when we come to resume proper, so I need
> > > Kevin to have a look at this.
> > >
> > > Apart from that it looks good.
> > >
> > > Stephen and Tony are trying to figure out the details of whether
> > > "active"
> > > is necessary or not in a related thread I think.
> Thanks for your comments.
>
> I've prepared diagram to illustrate how does this work:
>                                          +
>                                          |
>                                          |  .probe()
>                                          |
>                                    +-----v--------+
>                                    |              |
>                                    |  default     |
>                                    |              |
>                                    +----+--+------+
>                                         |  |
>                         pm_runtime_get()|  | pm_runtime_put()
>                        +----------------+  +------------+
>                        |                                |
>                 +------v------+ pm_runtime_put()+-------v-----+
>                 |             +----------------->             |
>     +----------->  Active     |pm_runtime_get() |   Idle      <----------+
>     |           |             <-----------------+             |          |
>     |           +-------+-----+                 +-------+-----+          |
>     |                   |.suspend_noirq()               |.suspend_noirq()|
>     |                   |                               |                |
>     |                   |                               |                |
>     |                   |                               |                |
>     |                   |                               |                |
>     |           +-------v-----+                 +-------v-----+          |
>     |           |             |                 |             |          |
>     +-----------+  Sleep      ------+           |  Sleep      +----------+
> .resume_noirq() |             |     |           |             |.resume_noirq()
>                 +-------|-----+     |           +-------------+
>                         |  Idle     |
>                         +-----------+
>
> The "Sleep" pinctrl state is optional - if "sleep" state isn't defined
> then "Idle" pinctrl state will be used during suspend.
>
> As per above pinctrl state transition diagram - I think, that:
> - if "idle" or "sleep" states are defined then "active" state have to be
> defined too.
> So, pinctrl core should detect such situation and generate a warning.
>
>  From my point of view, we should have "active" state - it would allow
> to avoid additional
> runtime overhead and handle properly the case when drivers are used as
> loadable modules.
> In this case, after boot, device's pinctrl registers can have HW default
> values (after reset) or
> can be configured to some safe (off) state from board file (board's
> "default" configuration).
> Driver module will activate its PINs when loaded and need to restore
> safe (off) PINs state when
> unloaded.
> As result, it seems, we should have "off" state which can be used when
> driver's module is removed.
>
> So, final list of default pnctrl states may be defined as "default",
> "active", "idle", "sleep", "off":
> - "active", "idle", "sleep": will be handled by omap_device core
> - "default", "off": will be handled by driver itself (or Device core).
>
>
>
> > Yes we should have that sorted out over next few weeks, so let's
> > just wait a little while on all these dynamic remuxing patches
> > to avoid churn.
> >
> > Regards,
> >
> > Tony
>
> Regards,
> - grygorii
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