linux-kernel - Re: [PATCH 3/4] drm/meson: dw-hdmi: Register a callback to disable the regulator

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Message-ID: <35fc622c-bebb-6111-9d08-e6b5433e75c5@baylibre.com>
Date:   Tue, 17 Nov 2020 09:55:04 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Marc Zyngier <maz@...nel.org>, Kevin Hilman <khilman@...libre.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        kernel-team@...roid.com, dri-devel@...ts.freedesktop.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] drm/meson: dw-hdmi: Register a callback to disable
 the regulator

On 16/11/2020 21:07, Marc Zyngier wrote:
> Removing the meson-dw-hdmi module results in the following splat:
> 
> i[   43.340509] WARNING: CPU: 0 PID: 572 at drivers/regulator/core.c:2125 _regulator_put.part.0+0x16c/0x174
> [...]
> [   43.454870] CPU: 0 PID: 572 Comm: modprobe Tainted: G        W   E     5.10.0-rc4-00049-gd274813a4de3-dirty #2147
> [   43.465042] Hardware name:  , BIOS 2021.01-rc2-00012-gde865f7ee1 11/16/2020
> [   43.471945] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--)
> [   43.477896] pc : _regulator_put.part.0+0x16c/0x174
> [   43.482638] lr : regulator_put+0x44/0x60
> [...]
> [   43.568715] Call trace:
> [   43.571132]  _regulator_put.part.0+0x16c/0x174
> [   43.575529]  regulator_put+0x44/0x60
> [   43.579067]  devm_regulator_release+0x20/0x2c
> [   43.583380]  release_nodes+0x1c8/0x2b4
> [   43.587087]  devres_release_all+0x44/0x6c
> [   43.591056]  __device_release_driver+0x1a0/0x23c
> [   43.595626]  driver_detach+0xcc/0x160
> [   43.599249]  bus_remove_driver+0x68/0xe0
> [   43.603130]  driver_unregister+0x3c/0x6c
> [   43.607011]  platform_driver_unregister+0x20/0x2c
> [   43.611678]  meson_dw_hdmi_platform_driver_exit+0x18/0x4a8 [meson_dw_hdmi]
> [   43.618485]  __arm64_sys_delete_module+0x1bc/0x294
> 
> as the HDMI regulator is still enabled on release.
> 
> In order to address this, register a callback that will deal with
> the disabling when the driver is unbound, solving the problem.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>

Fixes: 161a803fe32d ("drm/meson: dw_hdmi: Add support for an optional external 5V regulator")

> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 29a8ff41595d..68826cf9993f 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -941,6 +941,11 @@ static void meson_dw_hdmi_init(struct meson_dw_hdmi *meson_dw_hdmi)
>  
>  }
>  
> +static void meson_disable_regulator(void *data)
> +{
> +	regulator_disable(data);
> +}
> +
>  static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  				void *data)
>  {
> @@ -989,6 +994,10 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  		ret = regulator_enable(meson_dw_hdmi->hdmi_supply);
>  		if (ret)
>  			return ret;
> +		ret = devm_add_action_or_reset(dev, meson_disable_regulator,
> +					       meson_dw_hdmi->hdmi_supply);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	meson_dw_hdmi->hdmitx_apb = devm_reset_control_get_exclusive(dev,
> 

Acked-by: Neil Armstrong <narmstrong@...libre.com>