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

From: Neil Armstrong
Date: Tue Nov 17 2020 - 03:55:12 EST


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@xxxxxxxxxx>

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@xxxxxxxxxxxx>