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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Loic Pallardy <loic.pallardy@st.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 169/276] PM / core: Propagate dev->power.wakeup_path when no callbacks
Date:   Wed, 29 May 2019 20:05:27 -0700
Message-Id: <20190530030535.965554437@linuxfoundation.org>
In-Reply-To: <20190530030523.133519668@linuxfoundation.org>
References: <20190530030523.133519668@linuxfoundation.org>
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[ Upstream commit dc351d4c5f4fe4d0f274d6d660227be0c3a03317 ]

The dev->power.direct_complete flag may become set in device_prepare() in
case the device don't have any PM callbacks (dev->power.no_pm_callbacks is
set). This leads to a broken behaviour, when there is child having wakeup
enabled and relies on its parent to be used in the wakeup path.

More precisely, when the direct complete path becomes selected for the
child in __device_suspend(), the propagation of the dev->power.wakeup_path
becomes skipped as well.

Let's address this problem, by checking if the device is a part the wakeup
path or has wakeup enabled, then prevent the direct complete path from
being used.

Reported-by: Loic Pallardy <loic.pallardy@st.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[ rjw: Comment cleanup ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/base/power/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index a690fd4002605..4abd7c6531d9d 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1736,6 +1736,10 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 	if (dev->power.syscore)
 		goto Complete;
 
+	/* Avoid direct_complete to let wakeup_path propagate. */
+	if (device_may_wakeup(dev) || dev->power.wakeup_path)
+		dev->power.direct_complete = false;
+
 	if (dev->power.direct_complete) {
 		if (pm_runtime_status_suspended(dev)) {
 			pm_runtime_disable(dev);
-- 
2.20.1