linux-kernel - [PATCH] backlight: lp855x: Ensure regulators are disabled on probe failure

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Date:   Mon, 24 Feb 2020 14:07:48 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Milo Kim <milo.kim@...com>, Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, Jon Hunter <jonathanh@...dia.com>
Subject: [PATCH] backlight: lp855x: Ensure regulators are disabled on probe failure

If probing the LP885x backlight fails after the regulators have been
enabled, then the following warning is seen when releasing the
regulators ...

 WARNING: CPU: 1 PID: 289 at drivers/regulator/core.c:2051 _regulator_put.part.28+0x158/0x160
 Modules linked in: tegra_xudc lp855x_bl(+) host1x pwm_tegra ip_tables x_tables ipv6 nf_defrag_ipv6
 CPU: 1 PID: 289 Comm: systemd-udevd Not tainted 5.6.0-rc2-next-20200224 #1
 Hardware name: NVIDIA Jetson TX1 Developer Kit (DT)

 ...

 Call trace:
  _regulator_put.part.28+0x158/0x160
  regulator_put+0x34/0x50
  devm_regulator_release+0x10/0x18
  release_nodes+0x12c/0x230
  devres_release_all+0x34/0x50
  really_probe+0x1c0/0x370
  driver_probe_device+0x58/0x100
  device_driver_attach+0x6c/0x78
  __driver_attach+0xb0/0xf0
  bus_for_each_dev+0x68/0xc8
  driver_attach+0x20/0x28
  bus_add_driver+0x160/0x1f0
  driver_register+0x60/0x110
  i2c_register_driver+0x40/0x80
  lp855x_driver_init+0x20/0x1000 [lp855x_bl]
  do_one_initcall+0x58/0x1a0
  do_init_module+0x54/0x1d0
  load_module+0x1d80/0x21c8
  __do_sys_finit_module+0xe8/0x100
  __arm64_sys_finit_module+0x18/0x20
  el0_svc_common.constprop.3+0xb0/0x168
  do_el0_svc+0x20/0x98
  el0_sync_handler+0xf4/0x1b0
  el0_sync+0x140/0x180

Fix this by ensuring that the regulators are disabled, if enabled, on
probe failure.

Finally, ensure that the vddio regulator is disabled in the driver
remove handler.

Signed-off-by: Jon Hunter <jonathanh@...dia.com>
---
 drivers/video/backlight/lp855x_bl.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index f68920131a4a..e94932c69f54 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -456,7 +456,7 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 		ret = regulator_enable(lp->enable);
 		if (ret < 0) {
 			dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
-			return ret;
+			goto disable_supply;
 		}
 
 		/*
@@ -471,24 +471,34 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 	ret = lp855x_configure(lp);
 	if (ret) {
 		dev_err(lp->dev, "device config err: %d", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	ret = lp855x_backlight_register(lp);
 	if (ret) {
 		dev_err(lp->dev,
 			"failed to register backlight. err: %d\n", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
 	if (ret) {
 		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
-		return ret;
+		goto disable_vddio;
 	}
 
 	backlight_update_status(lp->bl);
+
 	return 0;
+
+disable_vddio:
+	if (lp->enable)
+		regulator_disable(lp->enable);
+disable_supply:
+	if (lp->supply)
+		regulator_disable(lp->supply);
+
+	return ret;
 }
 
 static int lp855x_remove(struct i2c_client *cl)
@@ -497,6 +507,8 @@ static int lp855x_remove(struct i2c_client *cl)
 
 	lp->bl->props.brightness = 0;
 	backlight_update_status(lp->bl);
+	if (lp->enable)
+		regulator_disable(lp->enable);
 	if (lp->supply)
 		regulator_disable(lp->supply);
 	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
-- 
2.17.1