On Tuesday, November 7, 2017 5:00:06 PM CET Tony Lindgren wrote: > * Florian Fainelli <f.fainelli@xxxxxxxxx> [171104 17:21]: > > > > > > On 11/04/2017 05:25 AM, Rafael J. Wysocki wrote: > > > On Friday, November 3, 2017 6:33:53 PM CET Tony Lindgren wrote: > > >> * Florian Fainelli <f.fainelli@xxxxxxxxx> [171103 17:04]: > > >>> On 11/03/2017 09:11 AM, Tony Lindgren wrote: > > >>> The pinctrl provider is losing its state, hence these two patches. > > >> > > >> OK > > >> > > >>>> Anyways, the context lost flag should be managed in the PM core for > > >>>> the device, so adding linux-pm and Rafael to Cc. > > >>> > > >>> I don't think it's that simple but sure, why not. > > >> > > >> Just having bool context_lost in struct dev_pm_info would probably > > >> be enough to allow drivers to deal with it. This flag could then > > >> be set for a device by power domain related code that knows if > > >> context got lost. > > > > > > Something like: if the driver sees "context_lost" set, it should restore > > > the context to the device from memory? > > > > That is what is being proposed here, except that the actual mechanism > > where this matters needs to be in the core pinctrl code, otherwise the > > state (context) is not restored due to a check that attempts not to > > (re)apply a previous state. > > > > > > > > But the it would also need to save the context beforehand, so why not to > > > restore it unconditionally on resume? > > > > That's what my original attempts did here: > > > > https://patchwork.kernel.org/patch/9598969/ > > > > but Linus rightfully requested this to be done differently, hence this > > attempt now to solve it in a slightly more flexible way based on DT > > properties. > > For runtime PM, restoring the state constantly is unnecessary and not > good for battery life. The logic can be just: > > 1. Device driver runtime PM suspend saves the state when needed > > 2. Device driver runtime PM resume checks if context_lost was set by > the bus or power domain code > > 3. If context was lost, device driver restores the state, or in some > cases may need re-run the driver register init related parts > to bring the driver back up, then clears the context_lost flag > > How about something like the following patch? So far only compile > tested with CONFIG_PM enabled. If that looks like the way to go, > I'll test it properly and add some comments for the functions and > post a proper patch :) Honestly, I'm not sure. I'd rather have a context_lost flag to start with and see how/if drivers will use that before adding any common infra for handling this. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
