linux-kernel - Re: [PATCH v9] drm/msm/dp: stop event kernel thread when DP unbind

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Message-ID: <CAE-0n505HQEu0Wmt17Y_AfTG+arD76kL7wpEFgeJKz6RRcQBxw@mail.gmail.com>
Date:   Mon, 18 Apr 2022 12:19:05 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
        airlied@...ux.ie, bjorn.andersson@...aro.org, daniel@...ll.ch,
        dmitry.baryshkov@...aro.org, robdclark@...il.com, sean@...rly.run,
        vkoul@...nel.org
Cc:     quic_abhinavk@...cinc.com, quic_aravindh@...cinc.com,
        quic_sbillaka@...cinc.com, freedreno@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9] drm/msm/dp: stop event kernel thread when DP unbind

Quoting Kuogee Hsieh (2022-04-15 16:47:25)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 01453db..5b289b9 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -266,9 +269,18 @@ static int dp_display_bind(struct device *dev, struct device *master,
>         }
>
>         rc = dp_register_audio_driver(dev, dp->audio);
> -       if (rc)
> +       if (rc) {
>                 DRM_ERROR("Audio registration Dp failed\n");
> +               goto end;
> +       }
>
> +       rc = dp_hpd_event_thread_start(dp);
> +       if (rc) {
> +               DRM_ERROR("Event thread create failed\n");

One thread DRM_ERROR()

> +               goto end;
> +       }
> +
> +       return 0;
>  end:
>         return rc;
>  }
> @@ -1132,12 +1149,19 @@ static int hpd_event_thread(void *data)
>         return 0;
>  }
>
> -static void dp_hpd_event_setup(struct dp_display_private *dp_priv)
> +static int dp_hpd_event_thread_start(struct dp_display_private *dp_priv)
>  {
> -       init_waitqueue_head(&dp_priv->event_q);
> -       spin_lock_init(&dp_priv->event_lock);
> +       /* set event q to empty */
> +       dp_priv->event_gndx = 0;
> +       dp_priv->event_pndx = 0;
> +
> +       dp_priv->ev_tsk = kthread_run(hpd_event_thread, dp_priv, "dp_hpd_handler");
> +       if (IS_ERR(dp_priv->ev_tsk)) {
> +               DRM_ERROR("failed to create DP event thread\n");

And another thread creation DRM_ERROR(). Can we just have one please
instead of two lines for something that probably never happens?

> +               return PTR_ERR(dp_priv->ev_tsk);
> +       }
>
> -       kthread_run(hpd_event_thread, dp_priv, "dp_hpd_handler");
> +       return 0;
>  }
>
>  static irqreturn_t dp_display_irq_handler(int irq, void *dev_id)