Hi
I add all in cc because mutt give me some trouble :(
Michael Trimarchi wrote:
> Drivers on embedded systems would be smart enough to know that some
> of the devices _should_ remain powered up, because they could still
> be useful even when the CPU wasn't running. The only obstacle is
> letting the drivers know when their devices actually _are_ in use
> and sometimes this is apparent only at the application level.
> The patch add the no_suspend attribute and it can be used by the
> the drivers to stop power down during suspend.
>
> Signed-off-by: Michael Trimarchi <trimarchi@xxxxxxxxxxxxxxxx>
> Cc: "Alan Stern" <stern@xxxxxxxxxxxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
> Cc: "Pavel Mackek" <pavel@xxxxxx>
> Cc: "Len Brown" <lenb@xxxxxxxxxx>
>
> ---
> drivers/base/power/main.c | 54 +++++++++++++++++++++++++++++++++++++++++++-
> drivers/base/power/power.h | 5 ++++
> include/linux/device.h | 1 +
> include/linux/pm.h | 3 ++
> 4 files changed, 62 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 69b4ddb..baae309 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -65,6 +65,45 @@ void device_pm_unlock(void)
> }
>
> /**
> + * device_set_no_suspend_enable - Mark the device as used by userspace
> + * application
> + */
> +void device_set_no_suspend_enable(struct device *dev, bool enable)
> +{
> + struct device *next;
> +
> + mutex_lock(&dpm_list_mtx);
> +
> + /* the new status is equal the old one */
> + if (dev->power.no_suspend == !!enable)
> + goto out;
> +
> + /* change the device status */
> + dev->power.no_suspend = !!enable;
> + if (dev->power.no_suspend)
> + dev->power.subtree_no_suspend = 0;
>
I find a bug here, i will fix.
It can be ok the rest of the code?
> +
> + list_for_each_entry_reverse(next, &dev->power.entry, power.entry) {
> + /*
> + * exit if we find a node with the same parent of the start
> + * device
> + */
> + if (dev->parent && next->parent == dev->parent)
> + break;
> +
> + if (next->parent) {
> + /* Propagate the status */
> + next->power.subtree_no_suspend =
> + device_no_suspend_enable(next->parent);
> + }
> + }
> +out:
> + mutex_unlock(&dpm_list_mtx);
> + return;
> +}
> +EXPORT_SYMBOL_GPL(device_set_no_suspend_enable);
> +
> +/**
> * device_pm_add - add a device to the list of active devices
> * @dev: Device to be added to the list
> */
> @@ -78,6 +117,11 @@ void device_pm_add(struct device *dev)
> if (dev->parent->power.status >= DPM_SUSPENDING)
> dev_warn(dev, "parent %s should not be sleeping\n",
> dev_name(dev->parent));
> + if (device_no_suspend_enable(dev->parent)) {
> + /* if the parent has suspend disable, propagate it
> + * to the new child */
> + dev->power.subtree_no_suspend = 1;
> + }
> } else if (transition_started) {
> /*
> * We refuse to register parentless devices while a PM
> @@ -87,7 +131,15 @@ void device_pm_add(struct device *dev)
> dev_WARN(dev, "Parentless device registered during a PM transaction\n");
> }
>
> - list_add_tail(&dev->power.entry, &dpm_list);
> + if (dev->parent) {
> + /*
> + * if the device has a parent insert just before it.
> + */
> + list_add_tail(&dev->power.entry, &(dev->parent)->power.entry);
> + }
> + else
> + list_add_tail(&dev->power.entry, &dpm_list);
> +
> mutex_unlock(&dpm_list_mtx);
> }
>
> diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
> index c7cb4fc..a997b20 100644
> --- a/drivers/base/power/power.h
> +++ b/drivers/base/power/power.h
> @@ -3,6 +3,11 @@ static inline void device_pm_init(struct device *dev)
> dev->power.status = DPM_ON;
> }
>
> +static inline int device_no_suspend_enable(struct device *dev)
> +{
> + return dev->power.no_suspend || dev->power.subtree_no_suspend;
> +}
> +
> #ifdef CONFIG_PM_SLEEP
>
> /*
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 2918c0e..74ca60d 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -496,6 +496,7 @@ extern struct device *device_find_child(struct device *dev, void *data,
> extern int device_rename(struct device *dev, char *new_name);
> extern int device_move(struct device *dev, struct device *new_parent,
> enum dpm_order dpm_order);
> +extern void device_set_no_suspend_enable(struct device *dev, bool enable);
>
> /*
> * Root device objects for grouping under /sys/devices
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 1d4e2d2..e664d63 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -319,6 +319,9 @@ struct dev_pm_info {
> pm_message_t power_state;
> unsigned can_wakeup:1;
> unsigned should_wakeup:1;
> + unsigned no_suspend:1;
> + unsigned subtree_no_suspend:1;
> +
> enum dpm_state status; /* Owned by the PM core */
> #ifdef CONFIG_PM_SLEEP
> struct list_head entry;
>
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