[PATCH 1/2] drm/i915: Only break encoder linked when linked to connector

[Egbert Eich <eich@suse.de>]

Depending on the SDVO output_flags SDVO may have multiple connectors
linking to the same encoder (in intel_connector->encoder->base).
Only one of those connectors should be active (ie link to the encoder
thru drm_connector->encoder.
If intel_connector_break_all_links() is called from intel_sanitize_crtc()
we may brake the crtc connection of an encoder thru an inactive connector
in which case intel_connector_break_all_links() will not be called again
for the active connector due to
   if (connector->encoder->base.crtc != &crtc->base)
                                continue;
in intel_sanitize_crtc().
This will however leave the drm_connector->encoder linkage for this
active connector in place. Subsequently this will cause multiple
warnings in intel_connector_check_state() to trigger and the driver
will eventually die in drm_encoder_crtc_ok() (because of crtc == NULL).

To avoid this break the encoder links only if the connector is active
(ie. has drm_connector->encoder set).

Signed-off-by: Egbert Eich <eich@suse.de>
---
 drivers/gpu/drm/i915/intel_display.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1390ab5..041f847 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11390,6 +11390,8 @@ static void
 intel_connector_break_all_links(struct intel_connector *connector)
 {
 	connector->base.dpms = DRM_MODE_DPMS_OFF;
+	if (!connector->base.encoder)
+		return;
 	connector->base.encoder = NULL;
 	connector->encoder->connectors_active = false;
 	connector->encoder->base.crtc = NULL;
-- 
1.8.4.5