On Mon, Feb 24, 2020 at 02:07:48PM +0000, Jon Hunter wrote:
> 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@xxxxxxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> ---
> 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
>
