linux-kernel - Re: [PATCH v3 11/33] drm/mediatek: mtk_hdmi: Unregister audio platform device on failure

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Message-ID: <8c5857cc3602342e9d1b4cf6689a0d5a044d9a1d.camel@mediatek.com>
Date: Mon, 23 Dec 2024 05:22:22 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
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	<mripard@...nel.org>, Jitao Shi (石记涛)
	<jitao.shi@...iatek.com>, "linux-mediatek@...ts.infradead.org"
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	<junzhi.zhao@...iatek.com>
Subject: Re: [PATCH v3 11/33] drm/mediatek: mtk_hdmi: Unregister audio
 platform device on failure

Hi, Angelo:

On Tue, 2024-12-17 at 16:43 +0100, AngeloGioacchino Del Regno wrote:
> External email : Please do not click links or open attachments until you have verified the sender or the content.
> 
> 
> The probe function of this driver may fail after registering the
> audio platform device: in that case, the state is not getting
> cleaned up, leaving this device registered.
> 
> Adding up to the mix, should the probe function of this driver
> return a probe deferral for N times, we're registering up to N
> audio platform devices and, again, never freeing them up.
> 
> To fix this, add a pointer to the audio platform device in the
> mtk_hdmi structure, and add a devm action to unregister it upon
> driver removal or probe failure.
> 
> Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi.c | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> index 59a8a81fa0ec..9131c2fdfba8 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> @@ -172,6 +172,7 @@ struct mtk_hdmi {
>         unsigned int sys_offset;
>         void __iomem *regs;
>         enum hdmi_colorspace csp;
> +       struct platform_device *audio_pdev;
>         struct hdmi_audio_param aud_param;
>         bool audio_enable;
>         bool powered;
> @@ -1662,6 +1663,11 @@ static const struct hdmi_codec_ops mtk_hdmi_audio_codec_ops = {
>         .no_capture_mute = 1,
>  };
> 
> +static void mtk_hdmi_unregister_audio_driver(void *data)
> +{
> +       platform_device_unregister(data);
> +}
> +
>  static int mtk_hdmi_register_audio_driver(struct device *dev)
>  {
>         struct mtk_hdmi *hdmi = dev_get_drvdata(dev);
> @@ -1671,13 +1677,22 @@ static int mtk_hdmi_register_audio_driver(struct device *dev)
>                 .i2s = 1,
>                 .data = hdmi,
>         };
> -       struct platform_device *pdev;
> +       int ret;
> 
> -       pdev = platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
> -                                            PLATFORM_DEVID_AUTO, &codec_data,
> -                                            sizeof(codec_data));
> -       if (IS_ERR(pdev))
> -               return PTR_ERR(pdev);
> +       hdmi->audio_pdev = platform_device_register_data(dev,
> +                                                        HDMI_CODEC_DRV_NAME,
> +                                                        PLATFORM_DEVID_AUTO,
> +                                                        &codec_data,
> +                                                        sizeof(codec_data));
> +       if (IS_ERR(hdmi->audio_pdev))
> +               return PTR_ERR(hdmi->audio_pdev);
> +
> +       ret = devm_add_action_or_reset(dev, mtk_hdmi_unregister_audio_driver,
> +                                      hdmi->audio_pdev);
> +       if (ret) {
> +               platform_device_unregister(hdmi->audio_pdev);

When devm_add_action_or_reset() fail, it would call mtk_hdmi_unregister_audio_driver() inside it.
So it's not necessary to call platform_device_unregister() here.

Regards,
CK

> +               return ret;
> +       }
> 
>         DRM_INFO("%s driver bound to HDMI\n", HDMI_CODEC_DRV_NAME);
>         return 0;
> --
> 2.47.0
>