* [PATCH][v2] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily
@ 2016-09-28 16:29 Chen Yu
2016-09-28 21:48 ` Rafael J. Wysocki
0 siblings, 1 reply; 3+ messages in thread
From: Chen Yu @ 2016-09-28 16:29 UTC (permalink / raw)
To: linux-pm
Cc: Pavel Machek, Len Brown, linux-kernel, Chen Yu, Andy Shevchenko,
Mika Westerberg, Rafael J . Wysocki, Lee Jones
We have report that the intel_lpss_prepare() takes too much time during
suspend, and this is because we first resume the devices from runtime
suspend by resume_lpss_device(), to make sure they are in proper state
before system suspend, which takes 100ms for each LPSS devices(PCI power
state from D3_cold to D0). And since resume_lpss_device() resumes the
devices synchronously, we might get huge latency if we have many
LPSS devices.
So first try is to use pm_request_resume() instead, to make the runtime
resume process asynchronously. Unfortunately the asynchronous runtime
resume relies on pm_wq, which is freezed at early stage. So we choose
another method, that is to avoid resuming runtime-suspended devices,
if they are already runtime suspended. This is safe because for LPSS
driver, the runtime suspend and system suspend are of the same
hook - i.e., intel_lpss_suspend(). And moreover, this device is
neither runtime wakeup source nor system wakeup source.
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
drivers/mfd/intel-lpss.c | 9 +++++++++
include/linux/pm.h | 3 +++
2 files changed, 12 insertions(+)
diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index 41b1138..2583db8 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -485,6 +485,15 @@ static int resume_lpss_device(struct device *dev, void *data)
int intel_lpss_prepare(struct device *dev)
{
/*
+ * This is safe because:
+ * 1. The runtime suspend and system suspend
+ * are of the same hook.
+ * 2. This device is neither runtime wakeup source
+ * nor system wakeup source.
+ */
+ if (pm_runtime_status_suspended(dev))
+ return DPM_DIRECT_COMPLETE;
+ /*
* Resume both child devices before entering system sleep. This
* ensures that they are in proper state before they get suspended.
*/
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 06eb353..5606ad9 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -786,4 +786,7 @@ enum dpm_order {
DPM_ORDER_DEV_LAST,
};
+/* The device is OK to remain runtime-suspended during suspend.*/
+#define DPM_DIRECT_COMPLETE 1
+
#endif /* _LINUX_PM_H */
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH][v2] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily
2016-09-28 16:29 [PATCH][v2] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily Chen Yu
@ 2016-09-28 21:48 ` Rafael J. Wysocki
2016-09-29 4:59 ` Chen Yu
0 siblings, 1 reply; 3+ messages in thread
From: Rafael J. Wysocki @ 2016-09-28 21:48 UTC (permalink / raw)
To: Chen Yu
Cc: Linux PM, Pavel Machek, Len Brown, Linux Kernel Mailing List,
Andy Shevchenko, Mika Westerberg, Rafael J . Wysocki, Lee Jones
On Wed, Sep 28, 2016 at 6:29 PM, Chen Yu <yu.c.chen@intel.com> wrote:
> We have report that the intel_lpss_prepare() takes too much time during
> suspend, and this is because we first resume the devices from runtime
> suspend by resume_lpss_device(), to make sure they are in proper state
> before system suspend, which takes 100ms for each LPSS devices(PCI power
> state from D3_cold to D0). And since resume_lpss_device() resumes the
> devices synchronously, we might get huge latency if we have many
> LPSS devices.
>
> So first try is to use pm_request_resume() instead, to make the runtime
> resume process asynchronously. Unfortunately the asynchronous runtime
> resume relies on pm_wq, which is freezed at early stage. So we choose
> another method, that is to avoid resuming runtime-suspended devices,
> if they are already runtime suspended. This is safe because for LPSS
> driver, the runtime suspend and system suspend are of the same
> hook - i.e., intel_lpss_suspend(). And moreover, this device is
> neither runtime wakeup source nor system wakeup source.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> drivers/mfd/intel-lpss.c | 9 +++++++++
> include/linux/pm.h | 3 +++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
> index 41b1138..2583db8 100644
> --- a/drivers/mfd/intel-lpss.c
> +++ b/drivers/mfd/intel-lpss.c
> @@ -485,6 +485,15 @@ static int resume_lpss_device(struct device *dev, void *data)
> int intel_lpss_prepare(struct device *dev)
> {
> /*
> + * This is safe because:
> + * 1. The runtime suspend and system suspend
> + * are of the same hook.
> + * 2. This device is neither runtime wakeup source
> + * nor system wakeup source.
> + */
> + if (pm_runtime_status_suspended(dev))
> + return DPM_DIRECT_COMPLETE;
> + /*
> * Resume both child devices before entering system sleep. This
> * ensures that they are in proper state before they get suspended.
> */
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 06eb353..5606ad9 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -786,4 +786,7 @@ enum dpm_order {
> DPM_ORDER_DEV_LAST,
> };
>
> +/* The device is OK to remain runtime-suspended during suspend.*/
/*
* Return this from system suspend/hibernation ->prepare() callback to
request the
* core to leave the device runtime-suspended during system suspend if possible.
*/
> +#define DPM_DIRECT_COMPLETE 1
> +
> #endif /* _LINUX_PM_H */
> --
But it is fine by me overall.
Thanks,
Rafael
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH][v2] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily
2016-09-28 21:48 ` Rafael J. Wysocki
@ 2016-09-29 4:59 ` Chen Yu
0 siblings, 0 replies; 3+ messages in thread
From: Chen Yu @ 2016-09-29 4:59 UTC (permalink / raw)
To: Rafael J. Wysocki
Cc: Linux PM, Pavel Machek, Len Brown, Linux Kernel Mailing List,
Andy Shevchenko, Mika Westerberg, Rafael J . Wysocki, Lee Jones
On Wed, Sep 28, 2016 at 11:48:40PM +0200, Rafael J. Wysocki wrote:
> On Wed, Sep 28, 2016 at 6:29 PM, Chen Yu <yu.c.chen@intel.com> wrote:
> > We have report that the intel_lpss_prepare() takes too much time during
> > suspend, and this is because we first resume the devices from runtime
> > suspend by resume_lpss_device(), to make sure they are in proper state
> > before system suspend, which takes 100ms for each LPSS devices(PCI power
> > state from D3_cold to D0). And since resume_lpss_device() resumes the
> > devices synchronously, we might get huge latency if we have many
> > LPSS devices.
> >
> > So first try is to use pm_request_resume() instead, to make the runtime
> > resume process asynchronously. Unfortunately the asynchronous runtime
> > resume relies on pm_wq, which is freezed at early stage. So we choose
> > another method, that is to avoid resuming runtime-suspended devices,
> > if they are already runtime suspended. This is safe because for LPSS
> > driver, the runtime suspend and system suspend are of the same
> > hook - i.e., intel_lpss_suspend(). And moreover, this device is
> > neither runtime wakeup source nor system wakeup source.
> >
> > Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Cc: Lee Jones <lee.jones@linaro.org>
> > Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> > ---
> > drivers/mfd/intel-lpss.c | 9 +++++++++
> > include/linux/pm.h | 3 +++
> > 2 files changed, 12 insertions(+)
> >
> > diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
> > index 41b1138..2583db8 100644
> > --- a/drivers/mfd/intel-lpss.c
> > +++ b/drivers/mfd/intel-lpss.c
> > @@ -485,6 +485,15 @@ static int resume_lpss_device(struct device *dev, void *data)
> > int intel_lpss_prepare(struct device *dev)
> > {
> > /*
> > + * This is safe because:
> > + * 1. The runtime suspend and system suspend
> > + * are of the same hook.
> > + * 2. This device is neither runtime wakeup source
> > + * nor system wakeup source.
> > + */
> > + if (pm_runtime_status_suspended(dev))
> > + return DPM_DIRECT_COMPLETE;
> > + /*
> > * Resume both child devices before entering system sleep. This
> > * ensures that they are in proper state before they get suspended.
> > */
> > diff --git a/include/linux/pm.h b/include/linux/pm.h
> > index 06eb353..5606ad9 100644
> > --- a/include/linux/pm.h
> > +++ b/include/linux/pm.h
> > @@ -786,4 +786,7 @@ enum dpm_order {
> > DPM_ORDER_DEV_LAST,
> > };
> >
> > +/* The device is OK to remain runtime-suspended during suspend.*/
>
> /*
> * Return this from system suspend/hibernation ->prepare() callback to
> request the
> * core to leave the device runtime-suspended during system suspend if possible.
> */
>
I've taken this comment in a new version, thanks!
> > +#define DPM_DIRECT_COMPLETE 1
> > +
> > #endif /* _LINUX_PM_H */
> > --
>
> But it is fine by me overall.
>
> Thanks,
> Rafael
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-09-29 4:51 UTC | newest]
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2016-09-28 16:29 [PATCH][v2] mfd: intel-lpss: Avoid resuming runtime-suspended lpss unnecessarily Chen Yu
2016-09-28 21:48 ` Rafael J. Wysocki
2016-09-29 4:59 ` Chen Yu
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