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Date: Wed, 13 Apr 2022 17:02:54 -0700
From: Stephen Boyd <swboyd@...omium.org>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
airlied@...ux.ie, bjorn.andersson@...aro.org, daniel@...ll.ch,
dmitry.baryshkov@...aro.org, robdclark@...il.com, sean@...rly.run,
vkoul@...nel.org
Cc: 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 v2] drm/msm/dp: enhance both connect and disconnect
pending_timeout handle
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.
> 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);
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