On Tue, 2021-10-26 at 17:39 +0200, Rafael J. Wysocki wrote:

On Mon, Oct 25, 2021 at 9:02 AM Chunfeng Yun <
chunfeng.yun@mediatek.com> wrote:

quoted

When the dedicated wake IRQ is level trigger, and it uses the
device's low-power status as the wakeup source, that means if the
device is not in low-power state, the wake IRQ will be triggered
if enabled; For this case, need enable the wake IRQ after running
the device's ->runtime_suspend() which make it enter low-power
state.

e.g.
Assume the wake IRQ is a low level trigger type, and the wakeup
signal comes from the low-power status of the device.
The wakeup signal is low level at running time (0), and becomes
high level when the device enters low-power state (runtime_suspend
(1) is called), a wakeup event at (2) make the device exit low-
power
state, then the wakeup signal also becomes low level.

                ------------------
               |           ^     ^|
----------------           |     | --------------
 |<---(0)--->|<--(1)--|   (3)   (2)    (4)

if enable the wake IRQ before running runtime_suspend during (0),
a wake IRQ will arise, it causes resume immediately;
it works if enable wake IRQ ( e.g. at (3) or (4)) after running
->runtime_suspend().

This patch introduces a new status WAKE_IRQ_DEDICATED_REVERSE to
optionally support enabling wake IRQ after running
->runtime_suspend().

Suggested-by: Rafael J. Wysocki <redacted>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>

I don't really have anything to add regarding the code.

The kerneldoc comments could be improved, but I can take care of this
when applying the patch.

Ok, thanks

Please collect ACKs for the remaining 2 patches in the series and I
will pick up all three.

The files (mtu3_plat.c, xhci-mtk.c) modified by other 2 patches are
maintained by myself, please pick up them, thanks a lot.

Thanks!

quoted

---
v4: changes according to Rafael's suggestions
    1. rename new flag as WAKE_IRQ_DEDICATED_REVERSE;
    2. add __dev_pm_set_dedicated_wake_irq() with flag parameter,
then
       rebuild dev_pm_set_dedicated_wake_irq() and add new api
       dev_pm_set_dedicated_wake_irq_reverse();
    3. rename the new added parameter as cond_disable in
       dev_pm_disable_wake_irq_check(), and also simplify its flow;
    4. modify some comments

v3: add new status suggested by Rafael

v2: add more commit message

  Use the falling edge trigger interrupt suggested by Ikjoon [1],
it
works well at firstly when only use this related wakeup source, but
encounter issues if use other wakeup sources to wakeup platform as
below steps:
1. use another wakeup source to wake up the suspended system;
2. the consumer's resume() will be called, and exits sleep state;
3. the consumer's wakeup signal will fall into low level, due to
   currently the wakeup irq is disabled, the wake-irq is pending;
4. the consumer tries to enter runtime suspend, but there is a
   pending wakeup irq, so will resume again, this will repeat
   endlessly.

  Send out the patch again for further discussion.

[1]: https://patchwork.kernel.org/patch/12190407

---
 drivers/base/power/power.h   |   7 ++-
 drivers/base/power/runtime.c |   6 ++-
 drivers/base/power/wakeirq.c | 101 +++++++++++++++++++++++++++--
------
 include/linux/pm_wakeirq.h   |   9 +++-
 4 files changed, 96 insertions(+), 27 deletions(-)

[...]

quoted

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel