Re: [PATCH] PM / Runtime: Only force-resume device if it has been force-suspended

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Hello.

On 03/03/2016 11:16 PM, Laurent Pinchart wrote:

   Noticed a few typos as well, some alreayd reported...

The pm_runtime_force_suspend() and pm_runtime_force_resume() helpers are
designed to help driver being RPM-centric by offering an easy way to
manager runtime PM state during system suspend and resume. The first

   Manage.

function will force the device into runtime suspend at system suspend
time, while the second one will perform the reverse operation at system
resume time.

However, the pm_runtime_force_resume() really forces resume, regarding

   Regardless.

of whether the device was running or already suspended before the call
to pm_runtime_force_suspend(). This results in devices being runtime
resumed at system resume time when they shouldn't.

Fix this by recording whether the device has been forcefully suspended
in pm_runtime_force_suspend() and condition resume in
pm_runtime_force_resume() to that state.

All current users of pm_runtime_force_resume() call the function
uncontionally in their system resume handler (some actually set it as

   Unconditionally.

the resume handler), all after calling pm_runtime_force_suspend() at
system suspend time. The change in behaviour should thus be safe.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
---
  drivers/base/power/runtime.c | 12 +++++++++---
  include/linux/pm.h           |  1 +
  2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 4c7055009bd6..ad2189294c9b 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
[...]
@@ -1483,13 +1485,13 @@ err:
  EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);

  /**
- * pm_runtime_force_resume - Force a device into resume state.
+ * pm_runtime_force_resume - Force a device into resume state if needed.
   * @dev: Device to resume.
   *
   * Prior invoking this function we expect the user to have brought the device
   * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
- * those actions and brings the device into full power. We update the runtime PM
- * status and re-enables runtime PM.
+ * those actions and bring the device back to its runtime PM state before forced
+ * suspension. We update the runtime PM status and re-enables runtime PM.

   Re-enable.

[...]

MBR, Sergei




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