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path: root/drivers/gpu/drm/i915/intel_dp.c
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Diffstat (limited to 'drivers/gpu/drm/i915/intel_dp.c')
-rw-r--r--drivers/gpu/drm/i915/intel_dp.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index cb8578b7e443..a4d80314e7f8 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1470,7 +1470,8 @@ intel_dp_link_down(struct intel_dp *intel_dp)
if (!HAS_PCH_CPT(dev) &&
I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) {
- struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.base.crtc);
+ struct drm_crtc *crtc = intel_dp->base.base.crtc;
+
/* Hardware workaround: leaving our transcoder select
* set to transcoder B while it's off will prevent the
* corresponding HDMI output on transcoder A.
@@ -1485,7 +1486,19 @@ intel_dp_link_down(struct intel_dp *intel_dp)
/* Changes to enable or select take place the vblank
* after being written.
*/
- intel_wait_for_vblank(dev, intel_crtc->pipe);
+ if (crtc == NULL) {
+ /* We can arrive here never having been attached
+ * to a CRTC, for instance, due to inheriting
+ * random state from the BIOS.
+ *
+ * If the pipe is not running, play safe and
+ * wait for the clocks to stabilise before
+ * continuing.
+ */
+ POSTING_READ(intel_dp->output_reg);
+ msleep(50);
+ } else
+ intel_wait_for_vblank(dev, to_intel_crtc(crtc)->pipe);
}
I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);

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