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

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Message-ID: <20200428070953.GI3559@dell>
Date:   Tue, 28 Apr 2020 08:09:53 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Milo Kim <milo.kim@...com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH] backlight: lp855x: Ensure regulators are disabled on
 probe failure

On Mon, 24 Feb 2020, 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@...dia.com>
> ---
>  drivers/video/backlight/lp855x_bl.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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