Re: [PATCH v6 07/11] drm/mediatek: dp: Avoid mutex locks if audio is not supported/enabled

[CK Hu (胡俊光)]

Hi, Angelo:

On Mon, 2023-07-17 at 16:14 +0200, AngeloGioacchino Del Regno wrote:
>  	 
> External email : Please do not click links or open attachments until
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>  If a controller (usually, eDP!) does not support audio, or audio is
> not
> enabled because the endpoint has no audio support, it's useless to
> lock
> a mutex only to unlock it right after because there's no
> .plugged_cb().
> 
> Check if the audio is supported and enabled before locking the mutex
> in
> mtk_dp_update_plugged_status(): if not, we simply return immediately.
> 
> While at it, since the update_plugged_status_lock mutex would not be
> used if the controller doesn't support audio at all, initialize it
> only if `audio_supported` is true.

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

> 
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 83e55f8dc84a..c1d1a882f1db 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1948,6 +1948,9 @@ static int mtk_dp_dt_parse(struct mtk_dp
> *mtk_dp,
>  
>  static void mtk_dp_update_plugged_status(struct mtk_dp *mtk_dp)
>  {
> +	if (!mtk_dp->data->audio_supported || !mtk_dp->audio_enable)
> +		return;
> +
>  	mutex_lock(&mtk_dp->update_plugged_status_lock);
>  	if (mtk_dp->plugged_cb && mtk_dp->codec_dev)
>  		mtk_dp->plugged_cb(mtk_dp->codec_dev,
> @@ -2520,11 +2523,11 @@ static int mtk_dp_probe(struct
> platform_device *pdev)
>  		return dev_err_probe(dev, ret,
>  				     "failed to request mediatek dptx
> irq\n");
>  
> -	mutex_init(&mtk_dp->update_plugged_status_lock);
> -
>  	platform_set_drvdata(pdev, mtk_dp);
>  
>  	if (mtk_dp->data->audio_supported) {
> +		mutex_init(&mtk_dp->update_plugged_status_lock);
> +
>  		ret = mtk_dp_register_audio_driver(dev);
>  		if (ret) {
>  			dev_err(dev, "Failed to register audio driver:
> %d\n",
> -- 
> 2.40.1