[Intel-gfx] [PATCH] drm/i915/icl: Disable DIP on MST ports with the transcoder clock still on

[Imre Deak]

According to BSpec the Data Island Packet should be disabled after
disabling the transcoder, but before the transcoder clock select is set
to none. On an ICL RVP, daisy-chained MST config not following this
leads to a hang with the following MCE when disabling the output:

[  870.948739] mce: [Hardware Error]: CPU 0: Machine Check Exception: 5 Bank 6: ba00000011000402
[  871.019212] mce: [Hardware Error]: RIP !INEXACT! 10:<ffffffff81aca652> {poll_idle+0x92/0xb0}
[  871.019212] mce: [Hardware Error]: TSC 135a261fe61
[  871.019212] mce: [Hardware Error]: PROCESSOR 0:706e5 TIME 1591739604 SOCKET 0 APIC 0 microcode 20
[  871.019212] mce: [Hardware Error]: Run the above through 'mcelog --ascii'
[  871.019212] mce: [Hardware Error]: Machine check: Processor context corrupt
[  871.019212] Kernel panic - not syncing: Fatal machine check
[  871.019212] Kernel Offset: disabled

Bspec: 4287

Fixes: fa37a213275c ("drm/i915: Stop sending DP SDPs on ddi disable")
Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
Cc: Uma Shankar <uma.shankar at intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c    | 4 +++-
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 8 ++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 96eaa4b39c68..50ccc6e30dc1 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3510,7 +3510,9 @@ static void intel_ddi_post_disable_dp(struct intel_atomic_state *state,
 					  INTEL_OUTPUT_DP_MST);
 	enum phy phy = intel_port_to_phy(dev_priv, encoder->port);
 
-	intel_dp_set_infoframes(encoder, false, old_crtc_state, old_conn_state);
+	if (!is_mst)
+		intel_dp_set_infoframes(encoder, false,
+					old_crtc_state, old_conn_state);
 
 	/*
 	 * Power down sink before disabling the port, otherwise we end
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index d18b406f2a7d..f29e51ce489c 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -397,6 +397,14 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 	 */
 	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port,
 				     false);
+
+	/*
+	 * BSpec 4287: disable DIP after the transcoder is disabled and before
+	 * the transcoder clock select is set to none.
+	 */
+	if (last_mst_stream)
+		intel_dp_set_infoframes(&intel_dig_port->base, false,
+					old_crtc_state, NULL);
 	/*
 	 * From TGL spec: "If multi-stream slave transcoder: Configure
 	 * Transcoder Clock Select to direct no clock to the transcoder"
-- 
2.23.1