linux-kernel - [PATCH 3.10 079/180] drm/radeon: Poll for both connect/disconnect on analog connectors

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Message-Id: <1471793510-13022-80-git-send-email-w@1wt.eu>
Date:   Sun, 21 Aug 2016 17:30:09 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Lyude <cpaul@...hat.com>, Alex Deucher <alexander.deucher@....com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 079/180] drm/radeon: Poll for both connect/disconnect on analog connectors

From: Lyude <cpaul@...hat.com>

commit 14ff8d48f2235295dfb3117693008e367b49cdb5 upstream.

DRM_CONNECTOR_POLL_CONNECT only enables polling for connections, not
disconnections. Because of this, we end up losing hotplug polling for
analog connectors once they get connected.

Easy way to reproduce:
 - Grab a machine with a radeon GPU and a VGA port
 - Plug a monitor into the VGA port, wait for it to update the connector
   from disconnected to connected
 - Disconnect the monitor on VGA, a hotplug event is never sent for the
   removal of the connector.

Originally, only using DRM_CONNECTOR_POLL_CONNECT might have been a good
idea since doing VGA polling can sometimes result in having to mess with
the DAC voltages to figure out whether or not there's actually something
there since VGA doesn't have HPD. Doing this would have the potential of
showing visible artifacts on the screen every time we ran a poll while a
VGA display was connected. Luckily, radeon_vga_detect() only resorts to
this sort of polling if the poll is forced, and DRM's polling helper
doesn't force it's polls.

Additionally, this removes some assignments to connector->polled that
weren't actually doing anything.

Cc: stable@...r.kernel.org
Signed-off-by: Lyude <cpaul@...hat.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/gpu/drm/radeon/radeon_connectors.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 1fbd38b..ea62810 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -1691,7 +1691,6 @@ radeon_add_atom_connector(struct drm_device *dev,
 						      1);
 			/* no HPD on analog connectors */
 			radeon_connector->hpd.hpd = RADEON_HPD_NONE;
-			connector->polled = DRM_CONNECTOR_POLL_CONNECT;
 			connector->interlace_allowed = true;
 			connector->doublescan_allowed = true;
 			break;
@@ -1889,8 +1888,10 @@ radeon_add_atom_connector(struct drm_device *dev,
 	}
 
 	if (radeon_connector->hpd.hpd == RADEON_HPD_NONE) {
-		if (i2c_bus->valid)
-			connector->polled = DRM_CONNECTOR_POLL_CONNECT;
+		if (i2c_bus->valid) {
+			connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+			                    DRM_CONNECTOR_POLL_DISCONNECT;
+		}
 	} else
 		connector->polled = DRM_CONNECTOR_POLL_HPD;
 
@@ -1962,7 +1963,6 @@ radeon_add_legacy_connector(struct drm_device *dev,
 					      1);
 		/* no HPD on analog connectors */
 		radeon_connector->hpd.hpd = RADEON_HPD_NONE;
-		connector->polled = DRM_CONNECTOR_POLL_CONNECT;
 		connector->interlace_allowed = true;
 		connector->doublescan_allowed = true;
 		break;
@@ -2047,10 +2047,13 @@ radeon_add_legacy_connector(struct drm_device *dev,
 	}
 
 	if (radeon_connector->hpd.hpd == RADEON_HPD_NONE) {
-		if (i2c_bus->valid)
-			connector->polled = DRM_CONNECTOR_POLL_CONNECT;
+		if (i2c_bus->valid) {
+			connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+			                    DRM_CONNECTOR_POLL_DISCONNECT;
+		}
 	} else
 		connector->polled = DRM_CONNECTOR_POLL_HPD;
+
 	connector->display_info.subpixel_order = subpixel_order;
 	drm_sysfs_connector_add(connector);
 }
-- 
2.8.0.rc2.1.gbe9624a