Re: [PATCH v3] drm/msm/dp: call dp_hpd_plug_handle()/unplug_handle() directly for external HPD

From: Abhinav Kumar
Date: Mon Apr 08 2024 - 15:44:08 EST




On 4/7/2024 11:48 AM, Bjorn Andersson wrote:
On Fri, Apr 05, 2024 at 08:15:47PM -0700, Abhinav Kumar wrote:
From: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
[..]
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index d80f89581760..bfb6dfff27e8 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1665,7 +1665,7 @@ void dp_bridge_hpd_notify(struct drm_bridge *bridge,
return;
if (!dp_display->link_ready && status == connector_status_connected)
- dp_add_event(dp, EV_HPD_PLUG_INT, 0, 0);
+ dp_hpd_plug_handle(dp, 0);

If I read the code correctly, and we get an external connect event
inbetween a previous disconnect and the related disable call, this
should result in a PLUG_INT being injected into the queue still.

Will that not cause the same problem?

Regards,
Bjorn


Yes, your observation is correct and I had asked the same question to kuogee before taking over this change and posting.

We will have to handle that case separately. I don't have a good solution yet for it without requiring further rework or we drop the below snippet.

if (state == ST_DISCONNECT_PENDING) {
/* wait until ST_DISCONNECTED */
dp_add_event(dp, EV_HPD_PLUG_INT, 0, 1); /* delay = 1 */
mutex_unlock(&dp->event_mutex);
return 0;
}

I will need sometime to address that use-case as I need to see if we can handle that better and then drop the the DISCONNECT_PENDING state to address this fully. But it needs more testing.

But, we will need this patch anyway because without this we will not be able to fix even the most regular and commonly seen case of basic connect/disconnect receiving complementary events.


else if (dp_display->link_ready && status == connector_status_disconnected)
- dp_add_event(dp, EV_HPD_UNPLUG_INT, 0, 0);
+ dp_hpd_unplug_handle(dp, 0);
}
--
2.43.2