drm/radeon/kms: fix shared ddc harder

This fixes a regression caused by b2ea4aa67bfd084834edd070e0a4a47857d6db59
due to the way shared ddc with multiple digital connectors was handled.

You generally have two cases where DDC lines are shared:
- HDMI + VGA
- HDMI + DVI-D

HDMI + VGA is easy to deal with because you can check the EDID for the
to see if the attached monitor is digital.  A shared DDC line with two
digital connectors is more complex.  You can't use the hdmi bits in the
EDID since they may not be there with DVI<->HDMI adapters.  In this case
all we can do is check the HPD pins to see which is connected as we have
no way of knowing using the EDID.

Reported-by: trapdoor6@gmail.com
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 14 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index f58f8bd8f77b..adccbc2c202c 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -771,14 +771,14 @@ static enum drm_connector_status radeon_dvi_detect(struct drm_connector *connect
                         } else
                                 ret = connector_status_connected;
 
-                        /* multiple connectors on the same encoder with the same ddc line
-                         * This tends to be HDMI and DVI on the same encoder with the
-                         * same ddc line.  If the edid says HDMI, consider the HDMI port
-                         * connected and the DVI port disconnected.  If the edid doesn't
-                         * say HDMI, vice versa.
+                        /* This gets complicated.  We have boards with VGA + HDMI with a
+                         * shared DDC line and we have boards with DVI-D + HDMI with a shared
+                         * DDC line.  The latter is more complex because with DVI<->HDMI adapters
+                         * you don't really know what's connected to which port as both are digital.
                          */
                         if (radeon_connector->shared_ddc && (ret == connector_status_connected)) {
                                 struct drm_device *dev = connector->dev;
+                                struct radeon_device *rdev = dev->dev_private;
                                 struct drm_connector *list_connector;
                                 struct radeon_connector *list_radeon_connector;
                                 list_for_each_entry(list_connector, &dev->mode_config.connector_list, head) {
@@ -788,15 +788,10 @@ static enum drm_connector_status radeon_dvi_detect(struct drm_connector *connect
                                         if (list_radeon_connector->shared_ddc &&
                                             (list_radeon_connector->ddc_bus->rec.i2c_id ==
                                              radeon_connector->ddc_bus->rec.i2c_id)) {
-                                                if (drm_detect_hdmi_monitor(radeon_connector->edid)) {
-                                                        if (connector->connector_type == DRM_MODE_CONNECTOR_DVID) {
-                                                                kfree(radeon_connector->edid);
-                                                                radeon_connector->edid = NULL;
-                                                                ret = connector_status_disconnected;
-                                                        }
-                                                } else {
-                                                        if ((connector->connector_type == DRM_MODE_CONNECTOR_HDMIA) ||
-                                                            (connector->connector_type == DRM_MODE_CONNECTOR_HDMIB)) {
+                                                /* cases where both connectors are digital */
+                                                if (list_connector->connector_type != DRM_MODE_CONNECTOR_VGA) {
+                                                        /* hpd is our only option in this case */
+                                                        if (!radeon_hpd_sense(rdev, radeon_connector->hpd.hpd)) {
                                                                 kfree(radeon_connector->edid);
                                                                 radeon_connector->edid = NULL;
                                                                 ret = connector_status_disconnected;