[PATCH 3/4] drm/i915: dp: Fail compute_config if link params need reset

[Sean Paul]

From: Sean Paul <seanpaul at chromium.org>

If the link parameters are incorrect, compute_config() can succeed with
bogus values. Since this is in no one's best interest, fail the compute
early.

Cc: stable at vger.kernel.org
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
 drivers/gpu/drm/i915/intel_dp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 07cd991d9ed6..1b6fc93182de 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2083,6 +2083,10 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	bool constant_n = drm_dp_has_quirk(&intel_dp->desc,
 					   DP_DPCD_QUIRK_CONSTANT_N);
 
+	/* Can't compute the config if the link parameters are out of date */
+	if (intel_dp->reset_link_params)
+		return false;
+
 	if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv) && port != PORT_A)
 		pipe_config->has_pch_encoder = true;
 
-- 
Sean Paul, Software Engineer, Google / Chromium OS