linux-kernel - Re: [PATCH 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown

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Message-ID: <1jwnyc41c6.fsf@starbuckisacylon.baylibre.com>
Date:   Mon, 23 Nov 2020 15:03:37 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Marc Zyngier <maz@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>
Cc:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Guillaume Tucker <guillaume.tucker@...labora.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 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown


On Fri 20 Nov 2020 at 10:42, Marc Zyngier <maz@...nel.org> wrote:

> The HDMI driver request clocks early, but never disable them, leaving
> the clocks on even when the driver is removed.
>
> Fix it by slightly refactoring the clock code, and register a devm
> action that will eventually disable/unprepare the enabled clocks.
>
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 43 ++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 7f8eea494147..29623b309cb1 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -145,8 +145,6 @@ struct meson_dw_hdmi {
>  	struct reset_control *hdmitx_apb;
>  	struct reset_control *hdmitx_ctrl;
>  	struct reset_control *hdmitx_phy;
> -	struct clk *hdmi_pclk;
> -	struct clk *venci_clk;
>  	struct regulator *hdmi_supply;
>  	u32 irq_stat;
>  	struct dw_hdmi *hdmi;
> @@ -946,6 +944,29 @@ static void meson_disable_regulator(void *data)
>  	regulator_disable(data);
>  }
>  
> +static void meson_disable_clk(void *data)
> +{
> +	clk_disable_unprepare(data);
> +}
> +
> +static int meson_enable_clk(struct device *dev, char *name)
> +{
> +	struct clk *clk;
> +	int ret;
> +
> +	clk = devm_clk_get(dev, name);
> +	if (IS_ERR(clk)) {
> +		dev_err(dev, "Unable to get %s pclk\n", name);
> +		return PTR_ERR(clk);
> +	}
> +
> +	ret = clk_prepare_enable(clk);
> +	if (!ret)
> +		ret = devm_add_action_or_reset(dev, meson_disable_clk,
> clk);

Thanks for fixing this Marc.

FYI, while it is fine to declare a function to disable the clocks, a quick
cast may avoid it

devm_add_action_or_reset(dev, (void(*)(void *))clk_disable_unprepare, clk);

> +
> +	return ret;
> +}
> +
>  static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  				void *data)
>  {
> @@ -1026,19 +1047,13 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  	if (IS_ERR(meson_dw_hdmi->hdmitx))
>  		return PTR_ERR(meson_dw_hdmi->hdmitx);
>  
> -	meson_dw_hdmi->hdmi_pclk = devm_clk_get(dev, "isfr");
> -	if (IS_ERR(meson_dw_hdmi->hdmi_pclk)) {
> -		dev_err(dev, "Unable to get HDMI pclk\n");
> -		return PTR_ERR(meson_dw_hdmi->hdmi_pclk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->hdmi_pclk);
> +	ret = meson_enable_clk(dev, "isfr");
> +	if (ret)
> +		return ret;
>  
> -	meson_dw_hdmi->venci_clk = devm_clk_get(dev, "venci");
> -	if (IS_ERR(meson_dw_hdmi->venci_clk)) {
> -		dev_err(dev, "Unable to get venci clk\n");
> -		return PTR_ERR(meson_dw_hdmi->venci_clk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->venci_clk);
> +	ret = meson_enable_clk(dev, "venci");
> +	if (ret)
> +		return ret;
>  
>  	dw_plat_data->regm = devm_regmap_init(dev, NULL, meson_dw_hdmi,
>  					      &meson_dw_hdmi_regmap_config);