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Message-ID: <20230919174813.26958-1-quic_abhinavk@quicinc.com>
Date: Tue, 19 Sep 2023 10:48:12 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: <dri-devel@...ts.freedesktop.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
CC: Abhinav Kumar <quic_abhinavk@...cinc.com>,
<freedreno@...ts.freedesktop.org>, <quic_jesszhan@...cinc.com>,
<quic_parellan@...cinc.com>, <laurent.pinchart@...asonboard.com>,
<andersson@...nel.org>, <jani.nikula@...ux.intel.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH] drm: remove drm_bridge_hpd_disable() from drm_bridge_connector_destroy()
drm_bridge_hpd_enable()/drm_bridge_hpd_disable() callbacks call into
the respective driver's hpd_enable()/hpd_disable() ops. These ops control
the HPD enable/disable logic which in some cases like MSM can be a
dedicate hardware block to control the HPD.
During probe_defer cases, a connector can be initialized and then later
destroyed till the probe is retried. During connector destroy in these
cases, the hpd_disable() callback gets called without a corresponding
hpd_enable() leading to an unbalanced state potentially causing even
a crash.
This can be avoided by the respective drivers maintaining their own
state logic to ensure that a hpd_disable() without a corresponding
hpd_enable() just returns without doing anything.
However, to have a generic fix it would be better to avoid the
hpd_disable() callback from the connector destroy path and let
the hpd_enable() / hpd_disable() balance be maintained by the
corresponding drm_bridge_connector_enable_hpd() /
drm_bridge_connector_disable_hpd() APIs which should get called by
drm_kms_helper_disable_hpd().
changes in v2:
- minor change in commit text (Dmitry)
Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
drivers/gpu/drm/drm_bridge_connector.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
index 1da93d5a1f61..c4dba39acfd8 100644
--- a/drivers/gpu/drm/drm_bridge_connector.c
+++ b/drivers/gpu/drm/drm_bridge_connector.c
@@ -187,12 +187,6 @@ static void drm_bridge_connector_destroy(struct drm_connector *connector)
struct drm_bridge_connector *bridge_connector =
to_drm_bridge_connector(connector);
- if (bridge_connector->bridge_hpd) {
- struct drm_bridge *hpd = bridge_connector->bridge_hpd;
-
- drm_bridge_hpd_disable(hpd);
- }
-
drm_connector_unregister(connector);
drm_connector_cleanup(connector);
--
2.40.1
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