* [PATCH 2/2] PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks @ 2021-05-28 9:12 Ulf Hansson 2021-05-28 15:27 ` Alan Stern 0 siblings, 1 reply; 3+ messages in thread From: Ulf Hansson @ 2021-05-28 9:12 UTC (permalink / raw) To: Rafael J . Wysocki, linux-pm Cc: Ulf Hansson, Saravana Kannan, Alan Stern, Adrian Hunter, Tony Lindgren, Kevin Hilman, Geert Uytterhoeven, linux-arm-kernel, linux-kernel We are currently allowing ->rpm_idle() callbacks to be unassigned without returning an error code from rpm_idle(). This has been useful to avoid boilerplate code in drivers. Let's take this approach a step further, by allowing unassigned ->runtime_suspend|resume() callbacks as well. In this way, a consumer/supplier device link can be used to let a consumer device be power managed through its supplier device, without requiring assigned ->runtime_suspend|resume() callbacks for the consumer device, for example. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- drivers/base/power/runtime.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 68bebbf81347..8a66eaf731e4 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -345,7 +345,7 @@ static void rpm_suspend_suppliers(struct device *dev) static int __rpm_callback(int (*cb)(struct device *), struct device *dev) __releases(&dev->power.lock) __acquires(&dev->power.lock) { - int retval, idx; + int retval = 0, idx; bool use_links = dev->power.links_count > 0; if (dev->power.irq_safe) { @@ -373,7 +373,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) } } - retval = cb(dev); + if (cb) + retval = cb(dev); if (dev->power.irq_safe) { spin_lock(&dev->power.lock); @@ -484,9 +485,6 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev) { int retval; - if (!cb) - return -ENOSYS; - if (dev->power.memalloc_noio) { unsigned int noio_flag; -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks 2021-05-28 9:12 [PATCH 2/2] PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks Ulf Hansson @ 2021-05-28 15:27 ` Alan Stern 2021-05-31 7:08 ` Ulf Hansson 0 siblings, 1 reply; 3+ messages in thread From: Alan Stern @ 2021-05-28 15:27 UTC (permalink / raw) To: Ulf Hansson Cc: Rafael J . Wysocki, linux-pm, Saravana Kannan, Adrian Hunter, Tony Lindgren, Kevin Hilman, Geert Uytterhoeven, linux-arm-kernel, linux-kernel On Fri, May 28, 2021 at 11:12:02AM +0200, Ulf Hansson wrote: > We are currently allowing ->rpm_idle() callbacks to be unassigned without > returning an error code from rpm_idle(). This has been useful to avoid > boilerplate code in drivers. Let's take this approach a step further, by > allowing unassigned ->runtime_suspend|resume() callbacks as well. > > In this way, a consumer/supplier device link can be used to let a consumer > device be power managed through its supplier device, without requiring > assigned ->runtime_suspend|resume() callbacks for the consumer device, for > example. > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > --- > drivers/base/power/runtime.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c > index 68bebbf81347..8a66eaf731e4 100644 > --- a/drivers/base/power/runtime.c > +++ b/drivers/base/power/runtime.c > @@ -345,7 +345,7 @@ static void rpm_suspend_suppliers(struct device *dev) > static int __rpm_callback(int (*cb)(struct device *), struct device *dev) > __releases(&dev->power.lock) __acquires(&dev->power.lock) > { > - int retval, idx; > + int retval = 0, idx; > bool use_links = dev->power.links_count > 0; > > if (dev->power.irq_safe) { > @@ -373,7 +373,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) > } > } > > - retval = cb(dev); > + if (cb) > + retval = cb(dev); > > if (dev->power.irq_safe) { > spin_lock(&dev->power.lock); > @@ -484,9 +485,6 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev) > { > int retval; > > - if (!cb) > - return -ENOSYS; This is a change in behavior, right? What about drivers or subsystems that don't support runtime PM and consequently don't have any RPM callbacks assigned? Also, assuming Rafael accepts this change, don't you also need to update the runtime-PM documentation? Alan Stern > - > if (dev->power.memalloc_noio) { > unsigned int noio_flag; > > -- > 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks 2021-05-28 15:27 ` Alan Stern @ 2021-05-31 7:08 ` Ulf Hansson 0 siblings, 0 replies; 3+ messages in thread From: Ulf Hansson @ 2021-05-31 7:08 UTC (permalink / raw) To: Alan Stern Cc: Rafael J . Wysocki, Linux PM, Saravana Kannan, Adrian Hunter, Tony Lindgren, Kevin Hilman, Geert Uytterhoeven, Linux ARM, Linux Kernel Mailing List On Fri, 28 May 2021 at 17:27, Alan Stern <stern@rowland.harvard.edu> wrote: > > On Fri, May 28, 2021 at 11:12:02AM +0200, Ulf Hansson wrote: > > We are currently allowing ->rpm_idle() callbacks to be unassigned without > > returning an error code from rpm_idle(). This has been useful to avoid > > boilerplate code in drivers. Let's take this approach a step further, by > > allowing unassigned ->runtime_suspend|resume() callbacks as well. > > > > In this way, a consumer/supplier device link can be used to let a consumer > > device be power managed through its supplier device, without requiring > > assigned ->runtime_suspend|resume() callbacks for the consumer device, for > > example. > > > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> > > --- > > drivers/base/power/runtime.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c > > index 68bebbf81347..8a66eaf731e4 100644 > > --- a/drivers/base/power/runtime.c > > +++ b/drivers/base/power/runtime.c > > @@ -345,7 +345,7 @@ static void rpm_suspend_suppliers(struct device *dev) > > static int __rpm_callback(int (*cb)(struct device *), struct device *dev) > > __releases(&dev->power.lock) __acquires(&dev->power.lock) > > { > > - int retval, idx; > > + int retval = 0, idx; > > bool use_links = dev->power.links_count > 0; > > > > if (dev->power.irq_safe) { > > @@ -373,7 +373,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) > > } > > } > > > > - retval = cb(dev); > > + if (cb) > > + retval = cb(dev); > > > > if (dev->power.irq_safe) { > > spin_lock(&dev->power.lock); > > @@ -484,9 +485,6 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev) > > { > > int retval; > > > > - if (!cb) > > - return -ENOSYS; > > This is a change in behavior, right? What about drivers or subsystems > that don't support runtime PM and consequently don't have any RPM > callbacks assigned? Yes, you are right. However, drivers/subsystems that support runtime PM should also call pm_runtime_enable() and if they don't, the rpm_callback() should not get called for them. Then, at least to me, I think it would be quite odd that a subsystem/driver that calls pm_runtime_enable(), would be checking return values from pm_runtime_get|put_*() for -ENOSYS? I mean, why bother calling pm_runtime_enable() in the first place? > > Also, assuming Rafael accepts this change, don't you also need to update > the runtime-PM documentation? Good point, thanks! Let me add a patch updating the docs. > > Alan Stern > Kind regards Uffe _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-05-31 7:10 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-05-28 9:12 [PATCH 2/2] PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks Ulf Hansson 2021-05-28 15:27 ` Alan Stern 2021-05-31 7:08 ` Ulf Hansson
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