This is a note to let you know that I've just added the patch titled

drm/radeon: Don't turn off DP sink when disconnected

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: drm-radeon-don-t-turn-off-dp-sink-when-disconnected.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 2681bc79eeb640562c932007bfebbbdc55bf6a7d Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Michel=20D=C3=A4nzer?= michel.daenzer@amd.com Date: Wed, 14 Mar 2018 18:14:04 +0100 Subject: drm/radeon: Don't turn off DP sink when disconnected MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Michel Dänzer michel.daenzer@amd.com

commit 2681bc79eeb640562c932007bfebbbdc55bf6a7d upstream.

Turning off the sink in this case causes various issues, because userspace expects it to stay on until it turns it off explicitly.

Instead, turn the sink off and back on when a display is connected again. This dance seems necessary for link training to work correctly.

Bugzilla: https://bugs.freedesktop.org/105308 Cc: stable@vger.kernel.org Reviewed-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Michel Dänzer michel.daenzer@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/gpu/drm/radeon/radeon_connectors.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-)

--- a/drivers/gpu/drm/radeon/radeon_connectors.c +++ b/drivers/gpu/drm/radeon/radeon_connectors.c @@ -90,25 +90,18 @@ void radeon_connector_hotplug(struct drm /* don't do anything if sink is not display port, i.e., * passive dp->(dvi|hdmi) adaptor */ - if (dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT) { - int saved_dpms = connector->dpms; - /* Only turn off the display if it's physically disconnected */ - if (!radeon_hpd_sense(rdev, radeon_connector->hpd.hpd)) { - drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF); - } else if (radeon_dp_needs_link_train(radeon_connector)) { - /* Don't try to start link training before we - * have the dpcd */ - if (!radeon_dp_getdpcd(radeon_connector)) - return; + if (dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT && + radeon_hpd_sense(rdev, radeon_connector->hpd.hpd) && + radeon_dp_needs_link_train(radeon_connector)) { + /* Don't start link training before we have the DPCD */ + if (!radeon_dp_getdpcd(radeon_connector)) + return;

- /* set it to OFF so that drm_helper_connector_dpms() - * won't return immediately since the current state - * is ON at this point. - */ - connector->dpms = DRM_MODE_DPMS_OFF; - drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON); - } - connector->dpms = saved_dpms; + /* Turn the connector off and back on immediately, which + * will trigger link training + */ + drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF); + drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON); } } }

Patches currently in stable-queue which might be from michel.daenzer@amd.com are

queue-4.9/drm-radeon-don-t-turn-off-dp-sink-when-disconnected.patch