Re: [PATCH v2 1/4] PM / core: Assign the wakeup_path status flag in __device_prepare()

On 30 December 2017 at 01:44, Rafael J. Wysocki [off-list ref] wrote:

On Fri, Dec 29, 2017 at 12:37 PM, Ulf Hansson [off-list ref] wrote:

quoted

The PM core in the device_prepare() phase, resets the wakeup_path status
flag to the value of device_may_wakeup(). This means if a ->prepare() or a
->suspend() callback for the device would update the device's wakeup
setting, this doesn't become reflected in the wakeup_path status flag.

In general this isn't a problem, because wakeup settings are not supposed
to be changed (via for example calling device_set_wakeup_enable()) during
any system wide suspend/resume phase.  Nevertheless there are some users,
which can be considered as legacy, that don't conform to this behaviour.

These legacy cases should be corrected, however until that is done, let's
address the issue from the PM core, by moving the assignment of the
wakeup_path status flag to the __device_suspend() phase and after the
->suspend() callback has been invoked.

Signed-off-by: Ulf Hansson <redacted>
---
 drivers/base/power/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 6e8cc5d..810e5fb 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c

@@ -1620,6 +1620,8 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
  End:
        if (!error) {
                dev->power.is_suspended = true;
+               if (device_may_wakeup(dev))
+                       dev->power.wakeup_path = true;
                dpm_propagate_to_parent(dev);
                dpm_clear_suppliers_direct_complete(dev);
        }

@@ -1744,7 +1746,7 @@ static int device_prepare(struct device *dev, pm_message_t state)

        device_lock(dev);

-       dev->power.wakeup_path = device_may_wakeup(dev);
+       dev->power.wakeup_path = false;

If you did "dev->power.wakeup_path = device_may_wakeup(dev)" in
__device_suspend(), it wouldn't need to be cleared here I guess?

No that doesn't work, because it may override the value of the flag
wrongly, in case a child's wakeup_path flag that is set and has been
propagated to the parent.

quoted

        if (dev->power.no_pm_callbacks) {
                ret = 1;        /* Let device go direct_complete */
--
2.7.4

Kind regards
Uffe