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From:   Mark Yacoub <markyacoub@chromium.org>
Cc:     seanpaul@chromium.org, markyacoub@google.com,
        markyacoub@chromium.org,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH] drm: Add a debug message when getting a prop is missing
Date:   Tue, 10 May 2022 14:28:03 -0400
Message-Id: <20220510182810.1223574-1-markyacoub@chromium.org>
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[Why]
If a connector property is attached but
drm_atomic_connector_get_property doesn't handle a case for it,
modeteset will crash with a segfault without.

[How]
Add a debug message indicating that a connector property is not handled
when user space is trying to read it.

TEST=modetest

Signed-off-by: Mark Yacoub <markyacoub@chromium.org>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index acb1ee93d206..36b0f664dd80 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -884,6 +884,12 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
 		return connector->funcs->atomic_get_property(connector,
 				state, property, val);
 	} else {
+		// LOG that the kernel is missing handling this property as a case here.
+		drm_dbg_atomic(
+			dev,
+			"[CONNECTOR:%d:%s] Get Property [PROP:%d:%s] is not handled\n",
+			connector->base.id, connector->name, property->base.id,
+			property->name);
 		return -EINVAL;
 	}
 
-- 
2.36.0.512.ge40c2bad7a-goog