linux-kernel - Re: [PATCH update] PM: Introduce core framework for run-time PM of I/O devices (rev. 15)

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Date:	Wed, 12 Aug 2009 19:37:15 +0900
From:	Magnus Damm <magnus.damm@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Alan Stern <stern@...land.harvard.edu>, Greg KH <gregkh@...e.de>,
	Pavel Machek <pavel@....cz>, Len Brown <lenb@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-pm mailing list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH update] PM: Introduce core framework for run-time PM of 
	I/O devices (rev. 15)

Hi Rafael,

On Mon, Aug 10, 2009 at 6:13 AM, Rafael J. Wysocki<rjw@...k.pl> wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> Subject: PM: Introduce core framework for run-time PM of I/O devices (rev. 15)
>
> Introduce a core framework for run-time power management of I/O
> devices.  Add device run-time PM fields to 'struct dev_pm_info'
> and device run-time PM callbacks to 'struct dev_pm_ops'.  Introduce
> a run-time PM workqueue and define some device run-time PM helper
> functions at the core level.  Document all these things.
>
> Special thanks to Alan Stern for his help with the design and
> multiple detailed reviews of the pereceding versions of this patch
> and to Magnus Damm for testing feedback.
>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>

Looking good! I have a few nitpicks below, but from a functional
perspective it's all good. I've tested v15 with platform device
drivers for I2C, UIO and framebuffer. Before adding my "Acked-by"  I
also want to test the V4L capture driver, but I need to wait a few
days until I can get my hands on such a hardware platform.

Thanks for folding in and fixing up the debug patch. I was able to
drop most remaining patches thanks to feedback from Alan. So the only
needed patch apart from this one (and the ones in your linux-next
branch) is the one in this micro-series: "PM: Runtime PM v15 for
Platform Devices 20090812".

> --- linux-2.6.orig/include/linux/pm.h
> +++ linux-2.6/include/linux/pm.h
[..]
>  struct dev_pm_info {
>        pm_message_t            power_state;
> -       unsigned                can_wakeup:1;
> -       unsigned                should_wakeup:1;
> +       unsigned int            can_wakeup:1;
> +       unsigned int            should_wakeup:1;
>        enum dpm_state          status;         /* Owned by the PM core */
> -#ifdef CONFIG_PM_SLEEP
> +#ifdef CONFIG_PM_SLEEP
>        struct list_head        entry;
>  #endif
> +#ifdef CONFIG_PM_RUNTIME
> +       struct timer_list       suspend_timer;
> +       unsigned long           timer_expires;
> +       struct work_struct      work;
> +       wait_queue_head_t       wait_queue;
> +       spinlock_t              lock;
> +       atomic_t                usage_count;
> +       atomic_t                child_count;

I suppose child_count has to be atomic?

> --- /dev/null
> +++ linux-2.6/drivers/base/power/runtime.c
[...]
> +int __pm_runtime_suspend(struct device *dev, bool from_wq)
> +       __releases(&dev->power.lock) __acquires(&dev->power.lock)
[...]
> +       if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_suspend) {
> +               spin_unlock_irq(&dev->power.lock);
> +
> +               retval = dev->bus->pm->runtime_suspend(dev);
> +
> +               spin_lock_irq(&dev->power.lock);
> +               dev->power.runtime_error = retval;
> +       } else {
> +               retval = -ENOSYS;
> +       }

Nit: { and } above do not follow the regular coding style.

> +int __pm_runtime_resume(struct device *dev, bool from_wq)
> +       __releases(&dev->power.lock) __acquires(&dev->power.lock)
[...]
> +       if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_resume) {
> +               spin_unlock_irq(&dev->power.lock);
> +
> +               retval = dev->bus->pm->runtime_resume(dev);
> +
> +               spin_lock_irq(&dev->power.lock);
> +               dev->power.runtime_error = retval;
> +       } else {
> +               retval = -ENOSYS;
> +       }

Same minor issue here.

Apart from that all is fine. Thank you.

/ magnus
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