Messages in this thread | | | Date | Thu, 18 Jul 2013 14:22:02 +0300 | From | Grygorii Strashko <> | Subject | Re: [PATCH 2/3] ARM: OMAP2+: omap_device: add pinctrl handling |
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On 07/18/2013 11:14 AM, Tony Lindgren wrote: > * Grygorii Strashko <grygorii.strashko@ti.com> [130717 10:11]: >> On 07/17/2013 06:38 PM, Tony Lindgren wrote: >>> * Grygorii Strashko <grygorii.strashko@ti.com> [130717 04:49]: >>>> Before switching to DT pinctrl states of OMAP IPs have been handled by hwmod >>>> framework. After switching to DT-boot the pinctrl handling was dropped from >>>> hwmod framework and, as it was recommended, OMAP IP's drivers have to be updated >>>> to handle pinctrl states by itself using pinctrl_pm_select_xx() helpers >>>> (see http://lists.infradead.org/pipermail/linux-arm-kernel/2013-June/173514.html) >>>> >>>> But this is not right for OMAP2+ SoC where real IPs state is controlled >>>> by omap_device core which enables/disables modules & clocks actually. >>> >>> I'm not convinced we should try to handle this in a generic way >>> as only some devices need dynamic remuxing of some pins. >>> >>>> For example, if OMAP I2C driver will handle pinctrl state during system wide >>>> suspend the following issue may occure: >>>> - suspend_noirq - I2C device can be still active because of PM auto-suspend >>>> |-_od_suspend_noirq >>>> |- omap_i2c_suspend_noirq >>>> |- PINs state set to SLEEP >>>> |- pm_generic_runtime_suspend >>>> |- omap_i2c_runtime_suspend() >>>> |- PINs state set to IDLE <--- *oops* PINs state is IDLE and not SLEEP >>>> |- omap_device_idle() >>>> |- omap_hwmod_idle() >>>> |- _idle() >>>> |- disbale module (sysc&clocks)
Above call sequence explains what's going on when .suspend_noirq() is called - .suspend_noirq() handler ==> _od_suspend_noirq() and it's set for all OMAP2+ devices.
>>> >>> And in this example you are assuming that you need separate idle and >>> sleep states, which is not true at least for most cases I've seen. >> >> I don't need both states (at least right now) :), but >> - if any OMAP2+ driver will have two states defined: "idle" and "sleep" >> - and if it will try to manage them from drivers callbacks only using >> pure calls to pinctrl_pm_select_xx() helpers >> >> the "idle" state will be selected during suspend and *not* "sleep". > > But the drivers have separate calls for runtime PM and suspend/resume?
Yes, but for OMAP2+ everything is handled by OMAP device framework :)
> >>> It is possible that am33xx needs separate idle and sleep states, but >>> most likely only for some pins. For omap[345] we can get away with >>> just the default state for most cases. >>> >> >> >> In case, if only "default" state is defined for device - nothing will >> be done by OMAP device framework for it (I mean any call to >> pinctrl_pm_select_xx() will do nothing - it just checks that there is >> no state and returns 0). > > If we want to automate something, it should be done at Linux generic > level rather than at omap "bus" level. That sort of relates to drivers > needing to know when they've lost context too, which should be > implemented in Linux generic way. > > Regards, > > Tony >
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