[v3] drm/msm/dp: stop event kernel thread when DP unbind

Current DP driver implementation, event thread is kept running
after DP display is unbind. This patch fix this problem by disabling
DP irq and stop event thread to exit gracefully at dp_display_unbind().

Changes in v2:
-- start event thread at dp_display_bind()

Changes in v3:
-- disable all HDP interrupts at unbind
-- replace dp_hpd_event_setup() with dp_hpd_event_thread_start()
-- replace dp_hpd_event_stop() with dp_hpd_event_thread_stop()
-- move init_waitqueue_head(&dp->event_q) to probe()
-- move spin_lock_init(&dp->event_lock) to probe()

Fixes: e91e3065a806 ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 42 ++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 10 deletions(-)

Quoting Kuogee Hsieh (2022-04-14 10:25:37)
> Current DP driver implementation, event thread is kept running
> after DP display is unbind. This patch fix this problem by disabling
> DP irq and stop event thread to exit gracefully at dp_display_unbind().
>
> Changes in v2:
> -- start event thread at dp_display_bind()
>
> Changes in v3:
> -- disable all HDP interrupts at unbind
> -- replace dp_hpd_event_setup() with dp_hpd_event_thread_start()
> -- replace dp_hpd_event_stop() with dp_hpd_event_thread_stop()
> -- move init_waitqueue_head(&dp->event_q) to probe()
> -- move spin_lock_init(&dp->event_lock) to probe()
>
> Fixes: e91e3065a806 ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c | 42 ++++++++++++++++++++++++++++---------
>  1 file changed, 32 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 01453db..0b9a96f 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -230,6 +231,29 @@ void dp_display_signal_audio_complete(struct msm_dp *dp_display)
>         complete_all(&dp->audio_comp);
>  }
>
> +static int hpd_event_thread(void *data);
> +
> +static int dp_hpd_event_thread_start(struct dp_display_private *dp_priv)
> +{
> +       int err = 0;

Drop local.

> +
> +       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");
> +               err = PTR_ERR(dp_priv->ev_tsk);

		return PTR_ERR(dp_priv->ev_tsk);

> +       }

Newline

> +       return err;

return 0;

> +}
> +
> +static void dp_hpd_event_thread_stop(struct dp_display_private *dp_priv)
> +{
> +       kthread_stop(dp_priv->ev_tsk);
> +
> +       /* reset event q to empty */
> +       dp_priv->event_gndx = 0;
> +       dp_priv->event_pndx = 0;
> +}
> +
>  static int dp_display_bind(struct device *dev, struct device *master,
>                            void *data)
>  {
> @@ -269,6 +293,7 @@ static int dp_display_bind(struct device *dev, struct device *master,
>         if (rc)
>                 DRM_ERROR("Audio registration Dp failed\n");
>
> +       rc = dp_hpd_event_thread_start(dp);

Forward declare this new function?

>  end:
>         return rc;
>  }
> @@ -280,6 +305,9 @@ static void dp_display_unbind(struct device *dev, struct device *master,
>         struct drm_device *drm = dev_get_drvdata(master);
>         struct msm_drm_private *priv = drm->dev_private;
>
> +       /* disable all HPD interrupts */
> +       dp_catalog_hpd_config_intr(dp->catalog, DP_DP_HPD_INT_MASK, false);
> +       dp_hpd_event_thread_stop(dp);
>         dp_power_client_deinit(dp->power);
>         dp_aux_unregister(dp->aux);
>         priv->dp[dp->id] = NULL;
> @@ -1054,7 +1082,7 @@ static int hpd_event_thread(void *data)
>
>         dp_priv = (struct dp_display_private *)data;
>
> -       while (1) {
> +       while (!kthread_should_stop()) {
>                 if (timeout_mode) {
>                         wait_event_timeout(dp_priv->event_q,
>                                 (dp_priv->event_pndx == dp_priv->event_gndx),
> @@ -1132,13 +1160,6 @@ static int hpd_event_thread(void *data)
>         return 0;
>  }
>
> -static void dp_hpd_event_setup(struct dp_display_private *dp_priv)
> -{
> -       init_waitqueue_head(&dp_priv->event_q);
> -       spin_lock_init(&dp_priv->event_lock);
> -
> -       kthread_run(hpd_event_thread, dp_priv, "dp_hpd_handler");
> -}

And then dp_hpd_event_thread_start() be defined here? The bind/unbind
functions should be moved to the bottom of this file because they're
probe/remove basically. Please do that in a followup patch.

>
>  static irqreturn_t dp_display_irq_handler(int irq, void *dev_id)
>  {