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Date: Fri, 15 Apr 2022 16:10:09 -0700
From: Kuogee Hsieh <quic_khsieh@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <robdclark@...il.com>, <sean@...rly.run>, <swboyd@...omium.org>,
<vkoul@...nel.org>, <daniel@...ll.ch>, <airlied@...ux.ie>,
<agross@...nel.org>, <bjorn.andersson@...aro.org>,
<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 v7] drm/msm/dp: stop event kernel thread when DP unbind
On 4/15/2022 3:48 PM, Dmitry Baryshkov wrote:
> On Sat, 16 Apr 2022 at 01:34, Kuogee Hsieh <quic_khsieh@...cinc.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@...cinc.com>
>> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>> Reviewed-by: Stephen Boyd <swboyd@...omium.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()
>> + 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?
>> 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
>>
>
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