linux-kernel - [PATCH v2 4/4] drm/dp_mst: Print errors on ACT timeouts

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Message-Id: <20200406221253.1307209-5-lyude@redhat.com>
Date:   Mon,  6 Apr 2020 18:12:53 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Sean Paul <sean@...rly.run>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/4] drm/dp_mst: Print errors on ACT timeouts

Although it's not unexpected for drm_dp_check_act_status() to fail due
to DPCD read failures (as the hub may have just been unplugged
suddenly), timeouts are a bit more worrying as they either mean we need
a longer timeout value, or we aren't setting up payload allocations
properly. So, let's start printing errors on timeouts.

Signed-off-by: Lyude Paul <lyude@...hat.com>
Cc: Sean Paul <sean@...rly.run>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index ce61964baa7c..0cbeb0f5c834 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4499,10 +4499,14 @@ int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
 				 status & DP_PAYLOAD_ACT_HANDLED || status < 0,
 				 100, timeout_ms * USEC_PER_MSEC);
 	if (ret < 0 && status >= 0) {
-		DRM_DEBUG_KMS("Failed to get ACT bit %d after %dms\n",
-			      status, timeout_ms);
+		DRM_ERROR("Failed to get ACT after %dms, last status: %02x\n",
+			  timeout_ms, status);
 		return -EINVAL;
 	} else if (status < 0) {
+		/*
+		 * Failure here isn't unexpected - the hub may have
+		 * just been unplugged
+		 */
 		DRM_DEBUG_KMS("Failed to read payload table status: %d\n",
 			      status);
 		return status;
-- 
2.25.1