linux-kernel - [PATCH 4.19 084/187] media: ov7740: fix runtime pm initialization

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Date:   Thu,  4 Apr 2019 10:47:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wenyou Yang <wenyou.yang@...rochip.com>,
        Akinobu Mita <akinobu.mita@...il.com>,
        Eugen Hristev <eugen.hristev@...rochip.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 084/187] media: ov7740: fix runtime pm initialization

4.19-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit 12aceee1f412c3ddc7750155fec06c906f14ab51 ]

The runtime PM of this device is enabled after v4l2_ctrl_handler_setup(),
and this makes this device's runtime PM usage count a negative value.

The ov7740_set_ctrl() tries to do something only if the device's runtime
PM usage counter is nonzero.

ov7740_set_ctrl()
{
	if (!pm_runtime_get_if_in_use(&client->dev))
		return 0;

	<do something>;

	pm_runtime_put(&client->dev);

	return ret;
}

However, the ov7740_set_ctrl() is called by v4l2_ctrl_handler_setup()
while the runtime PM of this device is not yet enabled.  In this case,
the pm_runtime_get_if_in_use() returns -EINVAL (!= 0).

Therefore we can't bail out of this function and the usage count is
decreased by pm_runtime_put() without increment.

This fixes this problem by enabling the runtime PM of this device before
v4l2_ctrl_handler_setup() so that the ov7740_set_ctrl() is always called
when the runtime PM is enabled.

Cc: Wenyou Yang <wenyou.yang@...rochip.com>
Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
Tested-by: Eugen Hristev <eugen.hristev@...rochip.com>
Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/i2c/ov7740.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/ov7740.c b/drivers/media/i2c/ov7740.c
index 605f3e25ad82..f5a1ee90a6c5 100644
--- a/drivers/media/i2c/ov7740.c
+++ b/drivers/media/i2c/ov7740.c
@@ -1101,6 +1101,9 @@ static int ov7740_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	pm_runtime_set_active(&client->dev);
+	pm_runtime_enable(&client->dev);
+
 	ret = ov7740_detect(ov7740);
 	if (ret)
 		goto error_detect;
@@ -1123,8 +1126,6 @@ static int ov7740_probe(struct i2c_client *client,
 	if (ret)
 		goto error_async_register;
 
-	pm_runtime_set_active(&client->dev);
-	pm_runtime_enable(&client->dev);
 	pm_runtime_idle(&client->dev);
 
 	return 0;
@@ -1134,6 +1135,8 @@ error_async_register:
 error_init_controls:
 	ov7740_free_controls(ov7740);
 error_detect:
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
 	ov7740_set_power(ov7740, 0);
 	media_entity_cleanup(&ov7740->subdev.entity);
 
-- 
2.19.1