linux-kernel - [PATCH 2/2] spi/s3c64xx: Fix doubled clock disable on suspend

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Date:	Mon, 21 Oct 2013 15:42:50 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Ben Dooks <ben-linux@...ff.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Mark Brown <broonie@...nel.org>
Cc:	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: [PATCH 2/2] spi/s3c64xx: Fix doubled clock disable on suspend

Fix doubled clock disable and unprepare during PM suspend which triggered
the warnings:

WARNING: at drivers/clk/clk.c:800 clk_disable+0x18/0x24()
Modules linked in:
CPU: 0 PID: 1745 Comm: sh Not tainted 3.10.14-01211-ge2549bb-dirty #62
[<c0015980>] (unwind_backtrace+0x0/0x138) from [<c0012a44>] (show_stack+0x10/0x14)
[<c0012a44>] (show_stack+0x10/0x14) from [<c0022818>] (warn_slowpath_common+0x4c/0x68)
[<c0022818>] (warn_slowpath_common+0x4c/0x68) from [<c0022850>] (warn_slowpath_null+0x1c/0x24)
[<c0022850>] (warn_slowpath_null+0x1c/0x24) from [<c036e274>] (clk_disable+0x18/0x24)
[<c036e274>] (clk_disable+0x18/0x24) from [<c02d5f78>] (s3c64xx_spi_suspend+0x28/0x54)
[<c02d5f78>] (s3c64xx_spi_suspend+0x28/0x54) from [<c02b3a54>] (platform_pm_suspend+0x2c/0x5c)
[<c02b3a54>] (platform_pm_suspend+0x2c/0x5c) from [<c02b8a30>] (dpm_run_callback+0x44/0x7c)
[<c02b8a30>] (dpm_run_callback+0x44/0x7c) from [<c02b8b70>] (__device_suspend+0x108/0x300)
[<c02b8b70>] (__device_suspend+0x108/0x300) from [<c02ba4e0>] (dpm_suspend+0x54/0x208)
[<c02ba4e0>] (dpm_suspend+0x54/0x208) from [<c0066bcc>] (suspend_devices_and_enter+0x98/0x458)
[<c0066bcc>] (suspend_devices_and_enter+0x98/0x458) from [<c0067150>] (pm_suspend+0x1c4/0x25c)
[<c0067150>] (pm_suspend+0x1c4/0x25c) from [<c0066044>] (state_store+0x6c/0xbc)
[<c0066044>] (state_store+0x6c/0xbc) from [<c0203290>] (kobj_attr_store+0x14/0x20)
[<c0203290>] (kobj_attr_store+0x14/0x20) from [<c0157530>] (sysfs_write_file+0xfc/0x164)
[<c0157530>] (sysfs_write_file+0xfc/0x164) from [<c00fd6b0>] (vfs_write+0xbc/0x1bc)
[<c00fd6b0>] (vfs_write+0xbc/0x1bc) from [<c00fdaf0>] (SyS_write+0x40/0x68)
[<c00fdaf0>] (SyS_write+0x40/0x68) from [<c000ea80>] (ret_fast_syscall+0x0/0x3c)

The clocks may be already disabled before suspending. Check PM runtime
suspend status and disable clocks only if device is not suspended.
During resume do not enable the clocks if device is runtime suspended.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
---
 drivers/spi/spi-s3c64xx.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 59f4fd9..8953178 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -1484,9 +1484,10 @@ static int s3c64xx_spi_suspend(struct device *dev)
 	if (ret)
 		return ret;
 
-	/* Disable the clock */
-	clk_disable_unprepare(sdd->src_clk);
-	clk_disable_unprepare(sdd->clk);
+	if (!pm_runtime_suspended(dev)) {
+		clk_disable_unprepare(sdd->clk);
+		clk_disable_unprepare(sdd->src_clk);
+	}
 
 	sdd->cur_speed = 0; /* Output Clock is stopped */
 
@@ -1502,9 +1503,10 @@ static int s3c64xx_spi_resume(struct device *dev)
 	if (sci->cfg_gpio)
 		sci->cfg_gpio();
 
-	/* Enable the clock */
-	clk_prepare_enable(sdd->src_clk);
-	clk_prepare_enable(sdd->clk);
+	if (!pm_runtime_suspended(dev)) {
+		clk_prepare_enable(sdd->src_clk);
+		clk_prepare_enable(sdd->clk);
+	}
 
 	s3c64xx_spi_hwinit(sdd, sdd->port_id);
 
-- 
1.7.9.5

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