linux-kernel - [PATCH 4.4 082/138] drm/radeon: Poll for both connect/disconnect on analog connectors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Date:	Thu, 18 Aug 2016 15:58:12 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Lyude <cpaul@...hat.com>,
	Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 4.4 082/138] drm/radeon: Poll for both connect/disconnect on analog connectors

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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.

Signed-off-by: Lyude <cpaul@...hat.com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/radeon/radeon_connectors.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -2058,7 +2058,6 @@ radeon_add_atom_connector(struct drm_dev
 							   RADEON_OUTPUT_CSC_BYPASS);
 			/* 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;
@@ -2308,8 +2307,10 @@ radeon_add_atom_connector(struct drm_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;
 
@@ -2385,7 +2386,6 @@ radeon_add_legacy_connector(struct drm_d
 					      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;
@@ -2470,10 +2470,13 @@ radeon_add_legacy_connector(struct drm_d
 	}
 
 	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_connector_register(connector);
 }