Quoting Kuogee Hsieh (2022-04-11 17:08:49)
> 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().
>
> Fixes: e91e3065a806 ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
> Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
Should add a Reported-by tag from Dmitry here.
> ---
> drivers/gpu/drm/msm/dp/dp_display.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 01453db..fa1ef8e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -273,6 +274,8 @@ static int dp_display_bind(struct device *dev, struct device *master,
> return rc;
> }
>
> +static void dp_hpd_event_stop(struct dp_display_private *dp_priv);
Why can't the function be defined here?
> +
> static void dp_display_unbind(struct device *dev, struct device *master,
> void *data)
> {
> @@ -280,6 +283,8 @@ 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_irq(dp->irq);
> + dp_hpd_event_stop(dp);
> dp_power_client_deinit(dp->power);
> dp_aux_unregister(dp->aux);
> priv->dp[dp->id] = NULL;
> @@ -1054,7 +1059,7 @@ 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),
> @@ -1137,7 +1142,22 @@ 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");
> + 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");
Why can't we error out? Why can't this kthread be started in probe?
> +}
> +
> +static void dp_hpd_event_stop(struct dp_display_private *dp_priv)
> +{
> + if (IS_ERR(dp_priv->ev_tsk))
> + return;
> +
> + kthread_stop(dp_priv->ev_tsk);
> +
> + /* reset event q to empty */
> + dp_priv->event_gndx = 0;
> + dp_priv->event_pndx = 0;
> }
>
