> -----Original Message-----
> From: Deak, Imre <imre.deak@xxxxxxxxx>
> Sent: Wednesday, June 10, 2020 3:36 AM
> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: Mun, Gwan-gyeong <gwan-gyeong.mun@xxxxxxxxx>; Shankar, Uma
> <uma.shankar@xxxxxxxxx>
> Subject: [PATCH] drm/i915/icl: Disable DIP on MST ports with the transcoder
> clock still on
>
> 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@xxxxxxxxx>
> Cc: Uma Shankar <uma.shankar@xxxxxxxxx>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
This is a good catch Imre. Would be good to know how you suspected this.
Reviewed-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> 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
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