Fwd: [PATCHv2] Input: omap4-keypad: Add pinctrl support
On Wed, Oct 31, 2012 at 9:10 PM, Kevin Hilman khil...@deeprootsystems.com wrote: Linus Walleij linus.wall...@linaro.org writes: piece of hardware, this would be the right thing to do, and I think the in-kernel examples are all simple, e.g. arch/arm/mach-omap2/powerdomain* is all about power domains and nothing else, FYI... that code isn't the same as PM domain. This sort of points to a core problem here. Our terminologies are ambiguous that we cannot understand each others code. As long as linux/pm_domain.h begins: /* * pm_domain.h - Definitions and headers related to device power domains. * But arguably that should just be patched (I think there are a few remnants in the code still implying that these things are only about power). That code is for the *hardware* powerdomains, not the software concept of PM domain. In OMAP, PM domain is implmented at the omap_device level. And omap_device is the abstraction of an IP block that knows about all the PM related register settings, clocks, HW powerdomain, voltage domain, PM related pin-muxing etc. etc.All of these things are abstracted in an omap_device, so that the PM domain implementation for OMAP looks rather simple (c.f. omap_device_pm_domain in arch/arm/plat-omap/omap_device.c.) OK following now... I think the lesser of two evils is the distributed approach, The pinctrl examples I've seen mentioned so far are all PM related (sleep, idle, wakeup, etc.) so to me I think they still belong in PM domains (and that's how we handle the PM related pins in OMAP.) Well, the pinctrl grabbers in these drivers are using these states also for platforms that do not even select CONFIG_PM. For example mach-nomadik is quite happy that the PL011 driver is thusly muxing in its pins. And would require refactoring to use PM domains. So basically this requirement comes down to: - When dealing with a SoC IP block driver - That need to multiplex pins - Then your SoC must select CONFIG_PM and CONFIG_PM_RUNTIME and CONFIG_PM_GENERIC_DOMAINS and implement proper domain handling hooks. Is this correct? And for Mark, Dmitry, does this correspond to your view? It's actually something that needs to be acknowledged by the ARM SoC maintainers, because they will be the ones telling all subarch maintainers to go implement full PM handling with these three frameworks whenever an SoC driver want to handle pins. Bascially all subsystem maintainers dealing with embedded SoCs need to be aligned on this as well... And IIUC not only pins but also silicon block clocks? I can surely fix these for my systems, but it really needs to be enforced widely or it will be a mess. I worry that the per-SoC power domain implementation which will live in arch/arm/mach-* as of today will become the new board file problem, overburdening the arch/* tree. Maybe I'm mistaken as to the size of these things, but just doing ls arch/arm/mach-omap2/powerdomain* makes me start worrying. Yes, I agree that this means more code/data in arch/arm/mach-*, but IMO, that's really where it belongs. It really is SoC integration details, and driver should really not know about it. OK we need feedback from ARM SoC on this. Yours, Linus Walleij -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Fwd: [PATCHv2] Input: omap4-keypad: Add pinctrl support
Linus Walleij linus.wall...@linaro.org writes: On Wed, Oct 31, 2012 at 9:10 PM, Kevin Hilman khil...@deeprootsystems.com wrote: Linus Walleij linus.wall...@linaro.org writes: piece of hardware, this would be the right thing to do, and I think the in-kernel examples are all simple, e.g. arch/arm/mach-omap2/powerdomain* is all about power domains and nothing else, FYI... that code isn't the same as PM domain. This sort of points to a core problem here. Our terminologies are ambiguous that we cannot understand each others code. As long as linux/pm_domain.h begins: /* * pm_domain.h - Definitions and headers related to device power domains. * But arguably that should just be patched (I think there are a few remnants in the code still implying that these things are only about power). Agreed. The terminology is confusing, and any situations like this in the code/comments/docs should be patched. When PM domains were introduced, I was the first to complain that we shouldn't use the term power domain so as not to be confused with HW concepts, so we settled on the term 'PM domain.' Ultimately, it's just a configurable grouping of devices whose callbacks happen during PM transitions. That code is for the *hardware* powerdomains, not the software concept of PM domain. In OMAP, PM domain is implmented at the omap_device level. And omap_device is the abstraction of an IP block that knows about all the PM related register settings, clocks, HW powerdomain, voltage domain, PM related pin-muxing etc. etc.All of these things are abstracted in an omap_device, so that the PM domain implementation for OMAP looks rather simple (c.f. omap_device_pm_domain in arch/arm/plat-omap/omap_device.c.) OK following now... I think the lesser of two evils is the distributed approach, The pinctrl examples I've seen mentioned so far are all PM related (sleep, idle, wakeup, etc.) so to me I think they still belong in PM domains (and that's how we handle the PM related pins in OMAP.) Well, the pinctrl grabbers in these drivers are using these states also for platforms that do not even select CONFIG_PM. For example mach-nomadik is quite happy that the PL011 driver is thusly muxing in its pins. And would require refactoring to use PM domains. If CONFIG_PM is disabled, then is it safe to assume that the pins in question are probably only done once at init time. I assume during -probe(). ? So basically this requirement comes down to: - When dealing with a SoC IP block driver - That need to multiplex pins - Then your SoC must select CONFIG_PM and CONFIG_PM_RUNTIME andb CONFIG_PM_GENERIC_DOMAINS and implement proper domain handling hooks. Is this correct? I would say yes. Currently, PM domains are the way to hook SoC-specific integration details into PM transitions. However, if what we want/need are only ways to introduce SoC-specific integration details into non-PM transitions (e.g. probe/remove), maybe bus notifiers would suffice here. e.g. you'd get a bus notifier when the device is added/attached and any init-time pinctrl setup could be done then. This still keeps drivers clean of SoC-specific integration data/code, and also allows that to happen whether or not PM features are enabled. Kevin -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
