On Monday, May 14, 2012, Marek Szyprowski wrote:
> Hi
>
> On 2012-05-11 22:51, Rafael J. Wysocki wrote:
> > On Thursday, May 10, 2012, Rafael J. Wysocki wrote:
> >> On Thursday, May 10, 2012, Marek Szyprowski wrote:
> >>> Hi Rafael,
> >>>
> >>> On Monday, May 07, 2012 8:45 PM Rafael J. Wysocki wrote:
> >>>
> >>>> On Monday, May 07, 2012, Marek Szyprowski wrote:
> >>>>> Hi Rafael,
> >>>>>
> >>>>> I'm sorry for a late reply, I was on holidays last week and just got
> >>>>> back to
> >>>>> the office.
> >>>>>
> >>>>> On Sunday, April 29, 2012 10:55 PM Rafael J. Wysocki wrote:
> >>>>>
> >>>>>> On Friday, April 06, 2012, Marek Szyprowski wrote:
> >>>>>>> Some bootloaders disable power domains on boot and the platform
> >>>>>>> startup
> >>>>>>> code registers them in the 'disabled' state. Current gen_pd code
> >>>>>>> assumed
> >>>>>>> that the devices can be registered only to the power domain which is
> >>>>>>> in
> >>>>>>> 'enabled' state and these devices are active at the time of the
> >>>>>>> registration. This is not correct in our case. This patch lets drivers
> >>>>>>> to be registered into 'disabled' power domains and finally solves
> >>>>>>> mysterious freezes and lack of resume/suspend calls on Samsung Exynos4
> >>>>>>> NURI and UniversalC210 platforms.
> >>>>>>>
> >>>>>>> Signed-off-by: Marek Szyprowski<m.szyprow...@samsung.com>
> >>>>>>> Signed-off-by: Kyungmin Park<kyungmin.p...@samsung.com>
> >>>>>>> ---
> >>>>>>> drivers/base/power/domain.c | 7 +------
> >>>>>>> 1 files changed, 1 insertions(+), 6 deletions(-)
> >>>>>>>
> >>>>>>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> >>>>>>> index 73ce9fb..05f5799f 100644
> >>>>>>> --- a/drivers/base/power/domain.c
> >>>>>>> +++ b/drivers/base/power/domain.c
> >>>>>>> @@ -1211,11 +1211,6 @@ int __pm_genpd_add_device(struct
> >>>>>>> generic_pm_domain *genpd, struct
> >>>>>> device *dev,
> >>>>>>>
> >>>>>>> genpd_acquire_lock(genpd);
> >>>>>>>
> >>>>>>> - if (genpd->status == GPD_STATE_POWER_OFF) {
> >>>>>>> - ret = -EINVAL;
> >>>>>>> - goto out;
> >>>>>>> - }
> >>>>>>> -
> >>>>>>> if (genpd->prepared_count> 0) {
> >>>>>>> ret = -EAGAIN;
> >>>>>>> goto out;
> >>>>>>> @@ -1239,7 +1234,7 @@ int __pm_genpd_add_device(struct
> >>>>>>> generic_pm_domain *genpd, struct
> >>>>>> device *dev,
> >>>>>>> dev_pm_get_subsys_data(dev);
> >>>>>>> dev->power.subsys_data->domain_data =&gpd_data->base;
> >>>>>>> gpd_data->base.dev = dev;
> >>>>>>> - gpd_data->need_restore = false;
> >>>>>>> + gpd_data->need_restore = true;
> >>>>>>
> >>>>>> I think that should be:
> >>>>>>
> >>>>>> + gpd_data->need_restore = genpd->status == GPD_STATE_POWER_OFF;
> >>>>>>
> >>>>>> Otherwise, on the next domain power off the device's state won't be
> >>>>>> saved.
> >>>>>>
> >>>>>>> list_add_tail(&gpd_data->base.list_node,&genpd->dev_list);
> >>>>>>> if (td)
> >>>>>>> gpd_data->td = *td;
> >>>>>
> >>>>> I've tested the above change and there is problem. Let me explain in
> >>>>> detail the
> >>>>> sw/hw configuration I have.
> >>>>>
> >>>>> There is a power domain and the device driver. The device itself also
> >>>>> has it's own
> >>>>> power management code (which enables and disables clocks). Some power
> >>>>> domains are
> >>>>> disabled by bootloader and some devices in the active power domains
> >>>>> have their
> >>>>> clocks disabled too. In the current runtime pm code the devices were
> >>>>> probed in
> >>>>> 'disabled' state and had to enable itself by calling
> >>>>> get_runtime_sync(). My initial
> >>>>> patch restored runtime pm handling to the old state (the same which was
> >>>>> with non
> >>>>> gen_pd based driver or no power domain driver at all, where runtime pm
> >>>>> was handled
> >>>>> by platform bus). If I apply your patch the runtime_restore
> >>>>
> >>>> I guess you mean .runtime_resume().
> >>>>
> >>>>> callback is not called on first driver probe for devices inside the
> >>>>> domain which
> >>>>> has been left enabled by the bootloader.
> >>>>
> >>>> I don't see why .probe() should depend on the runtime PM framework to
> >>>> call
> >>>> .runtime_resume() for it. It looks like .probe() could just call
> >>>> .runtime_resume() directly if needed.
> >>>>
> >>>> Besides, your change breaks existing code as I said.
> >>>
> >>> Before using gen_pd power domains we had the following flow of
> >>> calls/controls:
> >>>
> >>> 1. fimc_probe(fimd_pdev)
> >>> ...
> >>> 2. pm_runtime_enable(fimd_pdev->dev)
> >>> 3. pm_runtime_get_sync(fimd_pdev->dev)
> >>> 3a. parent device's runtime_resume()
> >>> 3b. fimc_runtime_resume(fimd_pdev->dev)
> >>> ...
> >>> 4. pm_runtime_put(fimd_pdev->dev)
> >>> ...
> >>> 5. (runtime put timer kicks off)
> >>> 5a. fimc_runtime_put(fimd_pdev->dev)
> >>> 5b. parent device's runtime_suspend()
> >>>
> >>> (this flow assumed that fimc device was the only child of its parent
> >>> platform device).
> >>>
> >>> Now with power gen_pd driver with my patch I get the following call
> >>> sequence:
> >>>
> >>> 1. fimc_probe(fimd_pdev)
> >>> ...
> >>> 2. pm_runtime_enable(fimd_pdev->dev)
> >>> 3. pm_runtime_get_sync(fimd_pdev->dev)
> >>> 3a. gen_pd pd_power_on(...)
> >>> 3b. fimc_runtime_resume(fimd_pdev->dev)
> >>> 4. pm_runtime_put(fimd_pdev->dev)
> >>> ...
> >>> 5. (runtime put timer kicks off)
> >>> 5a. fimc_runtime_put(fimd_pdev->dev)
> >>> 5b. gen_pd pd_power_off (...)
> >>>
> >>> so it works like before.
> >>>
> >>> Now with your suggested change I get following call sequence:
> >>>
> >>> 1. fimc_probe(fimc_pdev)
> >>> ...
> >>> 2. pm_runtime_enable(fimd_pdev->dev)
> >>> 3. pm_runtime_get_sync(fimd_pdev->dev)
> >>> (gen_pd finds that the power domain is already activated)
> >>> ...
> >>> 4. pm_runtime_put(fimd_pdev->dev)
> >>> ...
> >>> 5. (runtime put timer kicks off)
> >>> 5a. fimc_runtime_put(fimd_pdev->dev)
> >>> 5b. gen_pd pd_power_off (...)
> >>>
> >>> As you can notice in point 3, gen_pd driver checks its internal state,
> >>> finds that the power domain is already enabled and skips calling
> >>> fimc_runtime_resume(). This breaks the driver which worked fine before.
> >>
> >> It doesn't break anything, you're just using a wrong tool for a wrong
> >> purpose. Generic PM domains are not supposed to be a drop-in replacement
> >> for platform bus type!
> >>
> >>> Please notice that fimc_runtime_resume() does something completely
> >>> different than the power domain driver and those operations are essential
> >>> for getting the driver to work correctly.
> >>
> >> I don't quite understand what you mean here. What's the power domain
> >> driver
> >> in particular?
> >>
> >> Now, you can kind of make things work with my proposed modification of the
> >> patch if you make your platform code that adds the fmc device to the PM
> >> domain set its need_restore flag directly afterwards.
> >>
> >> So, you do
> >>
> >> pm_genpd_add_device(domain, fmc);
> >> fmc->power.subsys_data->domain_data->need_restore = true;
> >>
> >> Or you can actually modify __pm_genpd_add_device() so that it takes
> >> need_restore as an additional argument. That would be fine by me too so
> >> long
> >> as pm_genpd_add_device() worked in the same way as before.
> >>
> >> However, there is code already in the kernel that will break if you change
> >> __pm_genpd_add_device() to set need_restore unconditionally. Is that clear
> >> enough?
> >
> > I think we can use the
> >
> > + gpd_data->need_restore = genpd->status == GPD_STATE_POWER_OFF;
> >
> > variant of the $subject patch and add e helper for setting the need_restore
> > flag to it and use that helper along with pm_genpd_add_device() wherever
> > necessary.
> >
> > So, the entire patch might look like the one below.
> >
> > What do you think?
> >
> > Rafael
> >
> > ---
> > arch/arm/mach-exynos/pm_domains.c | 2 ++
> > drivers/base/power/domain.c | 27 +++++++++++++++++++++------
> > include/linux/pm_domain.h | 2 ++
> > 3 files changed, 25 insertions(+), 6 deletions(-)
> >
> > Index: linux/drivers/base/power/domain.c
> > ===================================================================
> > --- linux.orig/drivers/base/power/domain.c
> > +++ linux/drivers/base/power/domain.c
> > @@ -1302,11 +1302,6 @@ int __pm_genpd_add_device(struct generic
> >
> > genpd_acquire_lock(genpd);
> >
> > - if (genpd->status == GPD_STATE_POWER_OFF) {
> > - ret = -EINVAL;
> > - goto out;
> > - }
> > -
> > if (genpd->prepared_count> 0) {
> > ret = -EAGAIN;
> > goto out;
> > @@ -1329,7 +1324,7 @@ int __pm_genpd_add_device(struct generic
> > dev->power.subsys_data->domain_data =&gpd_data->base;
> > gpd_data->base.dev = dev;
> > list_add_tail(&gpd_data->base.list_node,&genpd->dev_list);
> > - gpd_data->need_restore = false;
> > + gpd_data->need_restore = genpd->status == GPD_STATE_POWER_OFF;
> > if (td)
> > gpd_data->td = *td;
> >
> > @@ -1457,6 +1452,26 @@ void pm_genpd_dev_always_on(struct devic
> > EXPORT_SYMBOL_GPL(pm_genpd_dev_always_on);
> >
> > /**
> > + * pm_genpd_dev_need_restore - Set/unset the device's "need restore" flag.
> > + * @dev: Device to set/unset the flag for.
> > + * @val: The new value of the device's "need restore" flag.
> > + */
> > +void pm_genpd_dev_need_restore(struct device *dev, bool val)
> > +{
> > + struct pm_subsys_data *psd;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&dev->power.lock, flags);
> > +
> > + psd = dev_to_psd(dev);
> > + if (psd&& psd->domain_data)
> > + to_gpd_data(psd->domain_data)->need_restore = val;
> > +
> > + spin_unlock_irqrestore(&dev->power.lock, flags);
> > +}
> > +EXPORT_SYMBOL_GPL(pm_genpd_dev_need_restore);
> > +
> > +/**
> > * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
> > * @genpd: Master PM domain to add the subdomain to.
> > * @subdomain: Subdomain to be added.
> > Index: linux/include/linux/pm_domain.h
> > ===================================================================
> > --- linux.orig/include/linux/pm_domain.h
> > +++ linux/include/linux/pm_domain.h
> > @@ -156,6 +156,7 @@ static inline int pm_genpd_of_add_device
> > extern int pm_genpd_remove_device(struct generic_pm_domain *genpd,
> > struct device *dev);
> > extern void pm_genpd_dev_always_on(struct device *dev, bool val);
> > +extern void pm_genpd_dev_need_restore(struct device *dev, bool val);
> > extern int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
> > struct generic_pm_domain *new_subdomain);
> > extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
> > @@ -201,6 +202,7 @@ static inline int pm_genpd_remove_device
> > return -ENOSYS;
> > }
> > static inline void pm_genpd_dev_always_on(struct device *dev, bool val) {}
> > +static inline void pm_genpd_dev_need_restore(struct device *dev, bool val)
> > {}
> > static inline int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
> > struct generic_pm_domain *new_sd)
> > {
> > Index: linux/arch/arm/mach-exynos/pm_domains.c
> > ===================================================================
> > --- linux.orig/arch/arm/mach-exynos/pm_domains.c
> > +++ linux/arch/arm/mach-exynos/pm_domains.c
> > @@ -123,6 +123,8 @@ static __init void exynos_pm_add_dev_to_
> > pr_info("%s: error in adding %s device to %s power"
> > "domain\n", __func__, dev_name(&pdev->dev),
> > pd->name);
> > + else
> > + pm_genpd_dev_need_restore(&pdev->dev, true);
> > }
> > }
> >
> >
>
> I'm fine with this solution. Thanks for your help!
OK, no problem.
Do you want me to apply the patch literally in the above form or should I skip
the arch/arm/mach-exynos/pm_domains.c change for now?
Rafael
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