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From: Prasad Sodagudi <psodagud@codeaurora.org>
To: gregkh@linuxfoundation.org, rjw@rjwysocki.net
Cc: len.brown@intel.com, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org, pavel@ucw.cz, psodagud@codeaurora.org
Subject: [PATCH v2] PM: sleep: core: Avoid setting power.must_resume to false
Date: Sun,  8 Aug 2021 09:10:27 -0700	[thread overview]
Message-ID: <1628439027-345496-1-git-send-email-psodagud@codeaurora.org> (raw)
In-Reply-To: <YQ4hj+blYxHdUl79@kroah.com>

There are variables(power.may_skip_resume and dev->power.must_resume)
and DPM_FLAG_MAY_SKIP_RESUME flags to control the resume of devices after
a system wide suspend transition.

Setting the DPM_FLAG_MAY_SKIP_RESUME flag means that the driver allows
its "noirq" and "early" resume callbacks to be skipped if the device
can be left in suspend after a system-wide transition into the working
state. PM core determines that the driver's "noirq" and "early" resume
callbacks should be skipped or not with dev_pm_skip_resume() function by
checking power.may_skip_resume variable.

power.must_resume variable is getting set to false in __device_suspend()
function without checking device's DPM_FLAG_MAY_SKIP_RESUME and
dev->power.usage_count variables. In problematic scenario, where
all the devices in the suspend_late stage are successful and some
device can fail to suspend in suspend_noirq phase. So some devices
successfully suspended in suspend_late stage are not getting chance
to execute __device_suspend_noirq() to set dev->power.must_resume
variable to true and not getting resumed in early_resume phase.

Add a check for device's DPM_FLAG_MAY_SKIP_RESUME flag before
setting power.must_resume variable in __device_suspend function.

Fixes: 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the resume phase")
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
---
 drivers/base/power/main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index d568772..9ee6987 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1642,7 +1642,11 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 	}
 
 	dev->power.may_skip_resume = true;
-	dev->power.must_resume = false;
+	if ((atomic_read(&dev->power.usage_count) <= 1) &&
+	     (dev_pm_test_driver_flags(dev, DPM_FLAG_MAY_SKIP_RESUME)))
+		dev->power.must_resume = false;
+	else
+		dev->power.must_resume = true;
 
 	dpm_watchdog_set(&wd, dev);
 	device_lock(dev);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project


  reply	other threads:[~2021-08-08 16:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 15:24 [PATCH] " Prasad Sodagudi
2021-08-03 17:16 ` Greg KH
2021-08-06 15:07   ` psodagud
2021-08-06 15:16     ` Greg KH
2021-08-07  6:00     ` Greg KH
2021-08-08 16:10       ` Prasad Sodagudi [this message]
2021-08-08 17:36         ` [PATCH v2] " Greg KH
2021-08-10 13:42 Prasad Sodagudi
2021-08-10 13:42 ` Prasad Sodagudi
2021-08-10 15:05   ` Greg KH
2021-08-10 15:06 ` Greg KH
2021-08-10 13:54 Prasad Sodagudi
2021-08-10 13:54 ` Prasad Sodagudi

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