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

[Shankar, Uma]

> -----Original Message-----
> From: Deak, Imre <imre.deak at intel.com>
> Sent: Wednesday, June 10, 2020 3:36 AM
> To: intel-gfx at lists.freedesktop.org
> Cc: Mun, Gwan-gyeong <gwan-gyeong.mun at intel.com>; Shankar, Uma
> <uma.shankar at intel.com>
> 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 at intel.com>
> Cc: Uma Shankar <uma.shankar at intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>


This is a good catch Imre. Would be good to know how you suspected this.
Reviewed-by: Uma Shankar <uma.shankar 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