Re: [PATCH v7] drm/msm/dp: stop event kernel thread when DP unbind

[Kuogee Hsieh <quic_khsieh@quicinc.com>]

On 4/15/2022 4:27 PM, Dmitry Baryshkov wrote:
> On Sat, 16 Apr 2022 at 02:10, Kuogee Hsieh <quic_khsieh@quicinc.com> wrote:
>>
>> On 4/15/2022 3:48 PM, Dmitry Baryshkov wrote:
>>> On Sat, 16 Apr 2022 at 01:34, Kuogee Hsieh <quic_khsieh@quicinc.com> wrote:
>>>> 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()
>>>>
>>>> Changes in v4:
>>>> -- relocate both dp_display_bind() and dp_display_unbind() to bottom of file
>>>>
>>>> Changes in v5:
>>>> -- cancel relocation of both dp_display_bind() and dp_display_unbind()
>>>>
>>>> Changes in v6:
>>>> -- move empty event q to dp_event_thread_start()
>>>>
>>>> Changes in v7:
>>>> -- call ktheread_stop() directly instead of dp_hpd_event_thread_stop() function
>>>>
>>>> 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>
>>>> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>>>> ---
>>>>    drivers/gpu/drm/msm/dp/dp_display.c | 31 ++++++++++++++++++++++++-------
>>>>    1 file changed, 24 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>>>> index 01453db..680e500 100644
>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>> @@ -113,6 +113,7 @@ struct dp_display_private {
>>>>           u32 hpd_state;
>>>>           u32 event_pndx;
>>>>           u32 event_gndx;
>>>> +       struct task_struct *ev_tsk;
>>>>           struct dp_event event_list[DP_EVENT_Q_MAX];
>>>>           spinlock_t event_lock;
>>>>
>>>> @@ -230,6 +231,8 @@ void dp_display_signal_audio_complete(struct msm_dp *dp_display)
>>>>           complete_all(&dp->audio_comp);
>>>>    }
>>>>
>>>> +static int dp_hpd_event_thread_start(struct dp_display_private *dp_priv);
>>>> +
>>>>    static int dp_display_bind(struct device *dev, struct device *master,
>>>>                              void *data)
>>>>    {
>>>> @@ -269,6 +272,7 @@ static int dp_display_bind(struct device *dev, struct device *master,
>>>>           if (rc)
>>>>                   DRM_ERROR("Audio registration Dp failed\n");
>>> I think I asked it in v3 and didn't get an answer:
>>> Isn't 'goto end' missing here?
>> I did follow you suggestion at v3 and made changes at
>> dp_hpd_event_thread_start()
> I'm asking about this place. Should we return an immediate error if
> audio registration has failed or not?

ok,

it is not in this patch.

I will make changes to it.

>>>> +       rc = dp_hpd_event_thread_start(dp);
>>> if (rc) { DRM_ERROR(....); goto end; }
>>> return 0;
>>>
>>> Please.
>> This is at dp_display_bind(),  "end" is the next statement why goto needed?
> To be explicit that this is a fatal error. Compare this to my question
> regarding the audio registration failure.
>
>>>>    end:
>>>>           return rc;
>>>>    }
>>>> @@ -280,6 +284,11 @@ 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);
>>>> +
>>>> +       kthread_stop(dp->ev_tsk);
>>>> +
>>>>           dp_power_client_deinit(dp->power);
>>>>           dp_aux_unregister(dp->aux);
>>>>           priv->dp[dp->id] = NULL;
>>>> @@ -1054,7 +1063,7 @@ 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),
>>>> @@ -1132,12 +1141,19 @@ 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");
>>>> +               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)
>>>> @@ -1266,7 +1282,10 @@ static int dp_display_probe(struct platform_device *pdev)
>>>>                   return -EPROBE_DEFER;
>>>>           }
>>>>
>>>> +       /* setup event q */
>>>>           mutex_init(&dp->event_mutex);
>>>> +       init_waitqueue_head(&dp->event_q);
>>>> +       spin_lock_init(&dp->event_lock);
>>>>
>>>>           /* Store DP audio handle inside DP display */
>>>>           dp->dp_display.dp_audio = dp->audio;
>>>> @@ -1441,8 +1460,6 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display)
>>>>
>>>>           dp = container_of(dp_display, struct dp_display_private, dp_display);
>>>>
>>>> -       dp_hpd_event_setup(dp);
>>>> -
>>>>           dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100);
>>>>    }
>>>>
>>>> --
>>>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>>>> a Linux Foundation Collaborative Project
>>>>
>
>