linux-kernel - [PATCH 3.16 317/346] i2c: qup: skip qup_i2c_suspend if the device is already runtime suspended

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Message-ID: <lsq.1479082460.66653839@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Wolfram Sang" <wsa@...-dreams.de>,
        "Sudeep Holla" <Sudeep.Holla@....com>,
        "Sudeep Holla" <sudeep.holla@....com>,
        "Andy Gross" <andy.gross@...aro.org>
Subject: [PATCH 3.16 317/346] i2c: qup: skip qup_i2c_suspend if the device
 is already runtime suspended

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Sudeep Holla <Sudeep.Holla@....com>

commit 331dcf421c34d227784d07943eb01e4023a42b0a upstream.

If the i2c device is already runtime suspended, if qup_i2c_suspend is
executed during suspend-to-idle or suspend-to-ram it will result in the
following splat:

WARNING: CPU: 3 PID: 1593 at drivers/clk/clk.c:476 clk_core_unprepare+0x80/0x90
Modules linked in:

CPU: 3 PID: 1593 Comm: bash Tainted: G        W       4.8.0-rc3 #14
Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
PC is at clk_core_unprepare+0x80/0x90
LR is at clk_unprepare+0x28/0x40
pc : [<ffff0000086eecf0>] lr : [<ffff0000086f0c58>] pstate: 60000145
Call trace:
 clk_core_unprepare+0x80/0x90
 qup_i2c_disable_clocks+0x2c/0x68
 qup_i2c_suspend+0x10/0x20
 platform_pm_suspend+0x24/0x68
 ...

This patch fixes the issue by executing qup_i2c_pm_suspend_runtime
conditionally in qup_i2c_suspend.

Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Reviewed-by: Andy Gross <andy.gross@...aro.org>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/i2c/busses/i2c-qup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c
@@ -724,7 +724,8 @@ static int qup_i2c_pm_resume_runtime(str
 #ifdef CONFIG_PM_SLEEP
 static int qup_i2c_suspend(struct device *device)
 {
-	qup_i2c_pm_suspend_runtime(device);
+	if (!pm_runtime_suspended(device))
+		return qup_i2c_pm_suspend_runtime(device);
 	return 0;
 }