Re: [PATCH v2] drm/msm/dp: enhance both connect and disconnect pending_timeout handle

[Kuogee Hsieh <quic_khsieh@quicinc.com>]

On 4/13/2022 5:02 PM, Stephen Boyd wrote:
> The subject is still misleading. It is fixing something. It may be
> enhancing it as well but it is clearly fixing it first.
>
> Quoting Kuogee Hsieh (2022-04-06 14:28:13)
>> dp_hpd_plug_handle() is responsible for setting up main link and send
>> uevent to notify user space framework to start video stream. Similarly,
>> dp_hdp_unplug_handle is responsible to send uevent to notify user space
>> framework to stop video stream and then tear down main link.
>> However there are rare cases, such as in the middle of system suspending,
>> that uevent could not be delivered to user space framework. Therefore
>> some kind of recover mechanism armed by timer need to be in place in the
>> case of user space framework does not respond to uevent.
>>
>> This patch have both dp_conenct_pending_timeout and
>> dp_disconnect_pending_timeout are used to stop video stream and tear down
>> main link and eventually restore DP driver state to known default
>> DISCONNECTED state in the case of timer fired due to framework does not
>> respond to uevent so that DP driver can recover itself gracefully at next
>> dongle unplug followed by plugin event.
>>
>> Changes in v2:
>> -- replace dp_display_usbpd_disconnect_cb with dp_display_notify_disconnect
> I'd prefer this part to be a different patch. It can come after the fix
> to ease backporting.
>
> Also, is there any response to Dmitry's question yet? I haven't seen
> anything.

Sorry, since our internal review does not like this approach.

I will upload new patch for review soon.

>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> index 2433edb..ffafe17 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> @@ -22,6 +22,7 @@ struct dp_ctrl {
>>   int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl);
>>   int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl);
>>   int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl);
>> +int dp_ctrl_off_link(struct dp_ctrl *dp_ctrl);
>>   int dp_ctrl_off(struct dp_ctrl *dp_ctrl);
>>   void dp_ctrl_push_idle(struct dp_ctrl *dp_ctrl);
>>   void dp_ctrl_isr(struct dp_ctrl *dp_ctrl);
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 178b774..a6200a5 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -451,11 +451,14 @@ static int dp_display_usbpd_configure_cb(struct device *dev)
>>
>>   static int dp_display_usbpd_disconnect_cb(struct device *dev)
> We shouldn't need to keep around an empty function.
>
>>   {
>> +       return 0;
>> +}
>> +
>> +static void dp_display_notify_disconnect(struct device *dev)
>> +{
>>          struct dp_display_private *dp = dev_get_dp_display_private(dev);
>>
>>          dp_add_event(dp, EV_USER_NOTIFICATION, false, 0);
>> -
>> -       return 0;
>>   }
>>
>>   static void dp_display_handle_video_request(struct dp_display_private *dp)
>> @@ -593,10 +596,16 @@ static int dp_connect_pending_timeout(struct dp_display_private *dp, u32 data)
>>
>>          mutex_lock(&dp->event_mutex);
>>
>> +       /*
>> +        * main link had been setup but video is not ready yet
>> +        * only tear down main link
>> +        */
>>          state = dp->hpd_state;
>>          if (state == ST_CONNECT_PENDING) {
>> -               dp->hpd_state = ST_CONNECTED;
>>                  DRM_DEBUG_DP("type=%d\n", dp->dp_display.connector_type);
>> +               dp_ctrl_off_link(dp->ctrl);
>> +               dp_display_host_phy_exit(dp);
>> +               dp->hpd_state = ST_DISCONNECTED;
>>          }
>>
>>          mutex_unlock(&dp->event_mutex);
>> @@ -645,6 +654,7 @@ static int dp_hpd_unplug_handle(struct dp_display_private *dp, u32 data)
>>                  if (dp->link->sink_count == 0) {
>>                          dp_display_host_phy_exit(dp);
>>                  }
>> +               dp_display_notify_disconnect(&dp->pdev->dev);
>>                  mutex_unlock(&dp->event_mutex);
>>                  return 0;
>>          }
>> @@ -661,19 +671,22 @@ static int dp_hpd_unplug_handle(struct dp_display_private *dp, u32 data)
>>                  return 0;
>>          }
>>
>> -       dp->hpd_state = ST_DISCONNECT_PENDING;
>> -
>>          /* disable HPD plug interrupts */
>>          dp_catalog_hpd_config_intr(dp->catalog, DP_DP_HPD_PLUG_INT_MASK, false);
>>
>>          /*
>>           * We don't need separate work for disconnect as
>>           * connect/attention interrupts are disabled
>> -        */
>> -       dp_display_usbpd_disconnect_cb(&dp->pdev->dev);
>> +       */
> This comment end is wrong. It should be unchanged.
>
>> +       dp_display_notify_disconnect(&dp->pdev->dev);
>>
>> -       /* start sentinel checking in case of missing uevent */
>> -       dp_add_event(dp, EV_DISCONNECT_PENDING_TIMEOUT, 0, DP_TIMEOUT_5_SECOND);
>> +       if (state == ST_DISPLAY_OFF) {
>> +               dp->hpd_state = ST_DISCONNECTED;
>> +       } else {
>> +               /* start sentinel checking in case of missing uevent */
>> +               dp_add_event(dp, EV_DISCONNECT_PENDING_TIMEOUT, 0, DP_TIMEOUT_5_SECOND);
>> +               dp->hpd_state = ST_DISCONNECT_PENDING;
>> +       }
>>
>>          /* signal the disconnect event early to ensure proper teardown */
>>          dp_display_handle_plugged_change(&dp->dp_display, false);
>> @@ -695,10 +708,16 @@ static int dp_disconnect_pending_timeout(struct dp_display_private *dp, u32 data
>>
>>          mutex_lock(&dp->event_mutex);
>>
>> +       /*
>> +        * main link had been set up and video is ready
>> +        * tear down main link, video stream and phy
>> +        */
>>          state =  dp->hpd_state;
>>          if (state == ST_DISCONNECT_PENDING) {
>> -               dp->hpd_state = ST_DISCONNECTED;
>>                  DRM_DEBUG_DP("type=%d\n", dp->dp_display.connector_type);
>> +               dp_ctrl_off(dp->ctrl);
>> +               dp_display_host_phy_exit(dp);
>> +               dp->hpd_state = ST_DISCONNECTED;
>>          }
>>
>>          mutex_unlock(&dp->event_mutex);