| Message ID | 1415917702-6742-2-git-send-email-khilman@kernel.org (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
On 13 November 2014 23:28, Kevin Hilman <khilman@kernel.org> wrote: > From: Kevin Hilman <khilman@linaro.org> > > It makes little sense to use generic power domains without runtime PM. > Also, since the complexities of handling the !PM_RUNTIME case are > causing more trouble and confusion than they're worth, let's simplify > the world by making genpd always enable runtime PM. I do agree that your above statement seems reasonable, even if can't really tell if that would break some SOCs use-cases. My concern is though, that I fear we will be taking short-cuts in genpd that might bite us later on, but I might be wrong. The reason for my concern is that on every other place, like in the subsystem level, driver core, PM core and of course in drivers - we need to cope with all the combinations of CONFIG_PM_SLEEP and CONFIG_PM_SLEEP. So theoretically, why shouldn't genpd be able to do that as well? > > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Geert Uytterhoeven <geert+renesas@glider.be> > Cc: Grygorii Strashko <grygorii.strashko@ti.com> > Signed-off-by: Kevin Hilman <khilman@linaro.org> > --- > kernel/power/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig > index 3d39cc0228e9..2a8c64d0a43c 100644 > --- a/kernel/power/Kconfig > +++ b/kernel/power/Kconfig > @@ -271,7 +271,7 @@ config PM_CLK > > config PM_GENERIC_DOMAINS > bool > - depends on PM > + select PM_RUNTIME Shouldn't we actually depend on PM_RUNTIME instead? > > config WQ_POWER_EFFICIENT_DEFAULT > bool "Enable workqueue power-efficient mode by default" > -- > 2.1.3 > Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 14 November 2014 08:26, Ulf Hansson <ulf.hansson@linaro.org> wrote: > On 13 November 2014 23:28, Kevin Hilman <khilman@kernel.org> wrote: >> From: Kevin Hilman <khilman@linaro.org> >> >> It makes little sense to use generic power domains without runtime PM. >> Also, since the complexities of handling the !PM_RUNTIME case are >> causing more trouble and confusion than they're worth, let's simplify >> the world by making genpd always enable runtime PM. > > I do agree that your above statement seems reasonable, even if can't > really tell if that would break some SOCs use-cases. > > My concern is though, that I fear we will be taking short-cuts in > genpd that might bite us later on, but I might be wrong. > > The reason for my concern is that on every other place, like in the > subsystem level, driver core, PM core and of course in drivers - we > need to cope with all the combinations of CONFIG_PM_SLEEP and > CONFIG_PM_SLEEP. So theoretically, why shouldn't genpd be able to do /s /CONFIG_PM_SLEEP /CONFIG_PM_RUNTIME > that as well? > >> >> Cc: Ulf Hansson <ulf.hansson@linaro.org> >> Cc: Geert Uytterhoeven <geert+renesas@glider.be> >> Cc: Grygorii Strashko <grygorii.strashko@ti.com> >> Signed-off-by: Kevin Hilman <khilman@linaro.org> >> --- >> kernel/power/Kconfig | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig >> index 3d39cc0228e9..2a8c64d0a43c 100644 >> --- a/kernel/power/Kconfig >> +++ b/kernel/power/Kconfig >> @@ -271,7 +271,7 @@ config PM_CLK >> >> config PM_GENERIC_DOMAINS >> bool >> - depends on PM >> + select PM_RUNTIME > > Shouldn't we actually depend on PM_RUNTIME instead? > >> >> config WQ_POWER_EFFICIENT_DEFAULT >> bool "Enable workqueue power-efficient mode by default" >> -- >> 2.1.3 >> > > Kind regards > Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Kevin, On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: > It makes little sense to use generic power domains without runtime PM. Does it? It still powers down the PM domains on system suspend (at least on my boards ;-) > Also, since the complexities of handling the !PM_RUNTIME case are > causing more trouble and confusion than they're worth, let's simplify > the world by making genpd always enable runtime PM. What do other people think? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Ulf, Ulf Hansson <ulf.hansson@linaro.org> writes: > On 13 November 2014 23:28, Kevin Hilman <khilman@kernel.org> wrote: >> From: Kevin Hilman <khilman@linaro.org> >> >> It makes little sense to use generic power domains without runtime PM. >> Also, since the complexities of handling the !PM_RUNTIME case are >> causing more trouble and confusion than they're worth, let's simplify >> the world by making genpd always enable runtime PM. > > I do agree that your above statement seems reasonable, even if can't > really tell if that would break some SOCs use-cases. Break in what way? > My concern is though, that I fear we will be taking short-cuts in > genpd that might bite us later on, but I might be wrong. > > The reason for my concern is that on every other place, like in the > subsystem level, driver core, PM core and of course in drivers - we > need to cope with all the combinations of CONFIG_PM_SLEEP and > CONFIG_PM_SLEEP. So theoretically, why shouldn't genpd be able to do > that as well? Good question, and one we need to figure out. (I meant to mark this patch as RFC for that reason.) I think the primary question is: why would one want to use genpd without runtime PM? I understand why one might want to use/test drivers with various combinations of PM_SLEEP and PM_RUNTIME, but I'm not seeing why we should need to support genpd without PM_RUNTIME enabled. In fact, on all the SoCs I've worked closely with, power domains, suspend/resume and runtime PM are all so closely intertwined that I can't imagine a useful scenario where they they are not all used together. If you care about PM, you turn them all on. If you don't, you turn them all off and ensure everything is enabled at boot. IMO, we're spending a lot of cycles supporting these various combinations and permutations and as a result are not really able to solve the real problems people are raising. Seems like most of the time a new feature/fixup/cleanup is proposed, the discussion always ends up around how to support things when this or that option is disabled, or some combination of kconfig options that weren't considered. I think we should simplify the config space permuations so we can focus on improving the frameworks. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Geert Uytterhoeven <geert@linux-m68k.org> writes: > Hi Kevin, > > On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: >> It makes little sense to use generic power domains without runtime PM. > > Does it? > It still powers down the PM domains on system suspend (at least on my > boards ;-) Sure, but your devices are also using runtime PM, so I'm not sure how does that change my statement above? >> Also, since the complexities of handling the !PM_RUNTIME case are >> causing more trouble and confusion than they're worth, let's simplify >> the world by making genpd always enable runtime PM. > > What do other people think? Yes, I'm curious also. This patch was supposed to be marked RFC. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, November 14, 2014 09:27:41 AM Kevin Hilman wrote: > Hi Ulf, > > Ulf Hansson <ulf.hansson@linaro.org> writes: > > > On 13 November 2014 23:28, Kevin Hilman <khilman@kernel.org> wrote: > >> From: Kevin Hilman <khilman@linaro.org> > >> > >> It makes little sense to use generic power domains without runtime PM. > >> Also, since the complexities of handling the !PM_RUNTIME case are > >> causing more trouble and confusion than they're worth, let's simplify > >> the world by making genpd always enable runtime PM. > > > > I do agree that your above statement seems reasonable, even if can't > > really tell if that would break some SOCs use-cases. > > Break in what way? > > > My concern is though, that I fear we will be taking short-cuts in > > genpd that might bite us later on, but I might be wrong. > > > > The reason for my concern is that on every other place, like in the > > subsystem level, driver core, PM core and of course in drivers - we > > need to cope with all the combinations of CONFIG_PM_SLEEP and > > CONFIG_PM_SLEEP. So theoretically, why shouldn't genpd be able to do > > that as well? > > Good question, and one we need to figure out. (I meant to mark this > patch as RFC for that reason.) > > I think the primary question is: why would one want to use genpd without > runtime PM? > > I understand why one might want to use/test drivers with various > combinations of PM_SLEEP and PM_RUNTIME, but I'm not seeing why we > should need to support genpd without PM_RUNTIME enabled. > > In fact, on all the SoCs I've worked closely with, power domains, > suspend/resume and runtime PM are all so closely intertwined that I > can't imagine a useful scenario where they they are not all used > together. If you care about PM, you turn them all on. If you don't, > you turn them all off and ensure everything is enabled at boot. > > IMO, we're spending a lot of cycles supporting these various > combinations and permutations and as a result are not really able to > solve the real problems people are raising. > > Seems like most of the time a new feature/fixup/cleanup is proposed, the > discussion always ends up around how to support things when this or that > option is disabled, or some combination of kconfig options that weren't > considered. > > I think we should simplify the config space permuations so we can focus > on improving the frameworks. Moreover, recently we've spend quite some time on discussing pretty much how to do runtime PM for CONFIG_PM_RUNTIME unset and really the conclusion to me is "Don't do that". There evidently are systems that require runtime PM (in some form) for basic functionality and it looks like all systems using genpd will fall into that category, more or less. Now, the runtime PM framework is what we have for handling this kind of stuff and I don't see a reason to pretend that it may be unnecessary. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, November 14, 2014 09:36:17 AM Kevin Hilman wrote: > Geert Uytterhoeven <geert@linux-m68k.org> writes: > > > Hi Kevin, > > > > On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: > >> It makes little sense to use generic power domains without runtime PM. > > > > Does it? > > It still powers down the PM domains on system suspend (at least on my > > boards ;-) > > Sure, but your devices are also using runtime PM, so I'm not sure how > does that change my statement above? Questions here are (1) how many users will actually want to disable PM_RUNTIME for systems using genpd (my sort of educated guess is "none") and (2) whether or not we need to power up stuff dynamically during initialization on systems using genpd (and several recent discussions indicate that the answer here is "yes, we need to do that"). > >> Also, since the complexities of handling the !PM_RUNTIME case are > >> causing more trouble and confusion than they're worth, let's simplify > >> the world by making genpd always enable runtime PM. > > > > What do other people think? > > Yes, I'm curious also. This patch was supposed to be marked RFC. I'm totally for making this change and I'm going to queue up this patch for 3.19, so if anyone sees a really good reason for not doing this, please let me know what that reason is as soon as you can. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Kevin, On Fri, Nov 14, 2014 at 6:36 PM, Kevin Hilman <khilman@kernel.org> wrote: >> On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: >>> It makes little sense to use generic power domains without runtime PM. >> >> Does it? >> It still powers down the PM domains on system suspend (at least on my >> boards ;-) > > Sure, but your devices are also using runtime PM, so I'm not sure how > does that change my statement above? I do mean with CONFIG_PM_RUNTIME turned off. If PM domain support is disabled, s2ram will not power down the PM domains. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri 2014-11-14 23:41:15, Rafael J. Wysocki wrote: > On Friday, November 14, 2014 09:36:17 AM Kevin Hilman wrote: > > Geert Uytterhoeven <geert@linux-m68k.org> writes: > > > > > Hi Kevin, > > > > > > On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: > > >> It makes little sense to use generic power domains without runtime PM. > > > > > > Does it? > > > It still powers down the PM domains on system suspend (at least on my > > > boards ;-) > > > > Sure, but your devices are also using runtime PM, so I'm not sure how > > does that change my statement above? > > Questions here are (1) how many users will actually want to disable PM_RUNTIME > for systems using genpd (my sort of educated guess is "none") and Well. Developers sometimes want to disable power management so that they don't have to debug it just now... disabling PM_RUNTIME is a way to do that. OTOH making code more complex to make new board bring-up easier may not be good idea.. Pavel
On Saturday, November 15, 2014 01:32:01 PM Geert Uytterhoeven wrote: > Hi Kevin, > > On Fri, Nov 14, 2014 at 6:36 PM, Kevin Hilman <khilman@kernel.org> wrote: > >> On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: > >>> It makes little sense to use generic power domains without runtime PM. > >> > >> Does it? > >> It still powers down the PM domains on system suspend (at least on my > >> boards ;-) > > > > Sure, but your devices are also using runtime PM, so I'm not sure how > > does that change my statement above? > > I do mean with CONFIG_PM_RUNTIME turned off. > > If PM domain support is disabled, s2ram will not power down the PM domains. But if PM_RUNTIME is enabled along with it, I don't think it will make much of a different, will it? Building the kernel with genpd and without PM_RUNTIME is possible today, but is it really useful? To me, it only seems to make people try to reinvent the wheel "because PM_RUNTIME may be unset". I have to say I'm seriously considering to make PM_SLEEP select PM_RUNTIME too as that would make quite a few things a *lot* simpler.
On Mon, Nov 17, 2014 at 2:22 AM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > On Saturday, November 15, 2014 01:32:01 PM Geert Uytterhoeven wrote: >> On Fri, Nov 14, 2014 at 6:36 PM, Kevin Hilman <khilman@kernel.org> wrote: >> >> On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: >> >>> It makes little sense to use generic power domains without runtime PM. >> >> >> >> Does it? >> >> It still powers down the PM domains on system suspend (at least on my >> >> boards ;-) >> > >> > Sure, but your devices are also using runtime PM, so I'm not sure how >> > does that change my statement above? >> >> I do mean with CONFIG_PM_RUNTIME turned off. >> >> If PM domain support is disabled, s2ram will not power down the PM domains. > > But if PM_RUNTIME is enabled along with it, I don't think it will make much > of a different, will it? That's true. > Building the kernel with genpd and without PM_RUNTIME is possible today, > but is it really useful? To me, it only seems to make people try to > reinvent the wheel "because PM_RUNTIME may be unset". > > I have to say I'm seriously considering to make PM_SLEEP select > PM_RUNTIME too as that would make quite a few things a *lot* simpler. I agree that it would simplify things, a reduce testing efforts. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
"Rafael J. Wysocki" <rjw@rjwysocki.net> writes: > On Saturday, November 15, 2014 01:32:01 PM Geert Uytterhoeven wrote: >> Hi Kevin, >> >> On Fri, Nov 14, 2014 at 6:36 PM, Kevin Hilman <khilman@kernel.org> wrote: >> >> On Thu, Nov 13, 2014 at 11:28 PM, Kevin Hilman <khilman@kernel.org> wrote: >> >>> It makes little sense to use generic power domains without runtime PM. >> >> >> >> Does it? >> >> It still powers down the PM domains on system suspend (at least on my >> >> boards ;-) >> > >> > Sure, but your devices are also using runtime PM, so I'm not sure how >> > does that change my statement above? >> >> I do mean with CONFIG_PM_RUNTIME turned off. >> >> If PM domain support is disabled, s2ram will not power down the PM domains. > > But if PM_RUNTIME is enabled along with it, I don't think it will make much > of a different, will it? > > Building the kernel with genpd and without PM_RUNTIME is possible today, > but is it really useful? To me, it only seems to make people try to > reinvent the wheel "because PM_RUNTIME may be unset". > > I have to say I'm seriously considering to make PM_SLEEP select > PM_RUNTIME too as that would make quite a few things a *lot* simpler. Yes. If that were the case, we woudn't need the pm_runtime_force_* calls either. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 3d39cc0228e9..2a8c64d0a43c 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -271,7 +271,7 @@ config PM_CLK config PM_GENERIC_DOMAINS bool - depends on PM + select PM_RUNTIME config WQ_POWER_EFFICIENT_DEFAULT bool "Enable workqueue power-efficient mode by default"