Hi, On Tue, Oct 30, 2012 at 09:16:34AM -0500, Jon Hunter wrote: > Hi Felipe, > > On 10/30/2012 02:09 AM, Felipe Balbi wrote: > > ... > > >> its bit of an issue to take care. How do you ensure that GPIO > >> does idle on SOC idle C-state attempts in such cases. Today that > >> job is done by omap_gpio_[prepare/resume]_for_idle. > > > > that's only there because we pm_runtime_get_sync() on gpio_request() and > > pm_runtime_put_sync() only on gpio_free(). > > > > That's the problem IMHO. And that's easy enough to 'fix': > > > > call pm_runtime_mark_last_busy(); pm_runtime_put_sync_autosuspend(); > > also on gpio_request() and pm_runtime_get_sync() on gpio_free(). > > Sounds like a good approach. I have been discussing with Kevin and I > need to look more at the resume handler as we are working around some > old issues in there and with this approach the resume following idle > will be delayed and we were not sure if there could be any implications > for omap2. I am hoping not, but we need to look into this. > > So I am wondering if we should just take Tim's original proposal for now > and then I will look into improving this long term. I really need to > clean-up the suspend/resume stuff for gpio and so may be we can make > that a separate change. What do you think? that'll cause a regression right ? > > The difficult part, IMHO, is to figure out what's a good autosuspend > > timeout to use. Some GPIO lines are used as IRQ lines on some devices, > > that means that the GPIO will be periodically triggered and, depending > > on our timeout, we will either loose IRQs or prevent power domain from > > idling. We could figure out a way to let board code to choose what it > > wants on a per-bank basis (maybe some extra DT attribute). > > I have also been bending Kevin's ear on this, this week and we were > wondering if we should make the default 0 for now as this will have the I believe you mean -1 here ;-) > same behaviour that we have today but would allow Tim to customise via > the sysfs for his specific app. sysfs might be too late for his platform. What if he needs NFS root (just wondering, not sure about his use case) ? -- balbi
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