[Intel-gfx] [PATCH] drm/i915/icl+: Prevent using non-TypeC AUX channels on TypeC ports

[Jani Nikula]

On Tue, 28 Apr 2020, Imre Deak <imre.deak at intel.com> wrote:
> On Tue, Apr 28, 2020 at 10:55:49AM +0300, Jani Nikula wrote:
>> On Thu, 23 Apr 2020, Imre Deak <imre.deak at intel.com> wrote:
>> > Using an AUX channel which by default belongs to a non-TypeC PHY won't
>> > work on a TypeC PHY, since - as a side-effect besides providing an AUX
>> > channel - the AUX channel power well affects power manangement specific
>> > to the TypeC subsystem. Using a TypeC AUX channel on a non-TypeC PHY
>> > would probably also cause problems, so for simplicity prevent both.
>> >
>> > This fixes at least an ICL-Y machine in CI, which has a buggy VBT
>> > setting AUX-B as an alternative channel for port C.
>> 
>> Is it a production machine?
>
> Yes.

*sigh*

Yeah I guess that settles it, we'll need this. :/

Ack.

BR,
Jani.




>
>> Not happy about adding stuff for pre-pro machines with buggy VBT.
>> It'll bite us later. It always has.
>
> If there is a buggy VBT with this issue it will cause a problem
> somewhere down the pipeline which is difficult to track down, power well
> timeouts, machine hangs etc. I would like to catch this early and avoid
> having to spend time debugging these other issues.
>
>> Also, hate to see VBT code call into intel_display.c (intel_phy_is_tc).
>
> That's the way to determine if a port/PHY is TypeC on a platform or not.
>
> --Imre
>
>> 
>> BR,
>> Jani.
>> 
>> 
>> >
>> > Signed-off-by: Imre Deak <imre.deak at intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/display/intel_bios.c | 84 +++++++++++++++--------
>> >  1 file changed, 57 insertions(+), 27 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
>> > index 839124647202..10d463723d12 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_bios.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_bios.c
>> > @@ -1538,11 +1538,38 @@ static enum port get_port_by_aux_ch(struct drm_i915_private *i915, u8 aux_ch)
>> >  	return PORT_NONE;
>> >  }
>> >  
>> > +static enum aux_ch
>> > +intel_bios_port_info_aux_ch(const struct ddi_vbt_port_info *info)
>> > +{
>> > +	switch (info->alternate_aux_channel) {
>> > +	case DP_AUX_A:
>> > +		return AUX_CH_A;
>> > +	case DP_AUX_B:
>> > +		return AUX_CH_B;
>> > +	case DP_AUX_C:
>> > +		return AUX_CH_C;
>> > +	case DP_AUX_D:
>> > +		return AUX_CH_D;
>> > +	case DP_AUX_E:
>> > +		return AUX_CH_E;
>> > +	case DP_AUX_F:
>> > +		return AUX_CH_F;
>> > +	case DP_AUX_G:
>> > +		return AUX_CH_G;
>> > +	default:
>> > +		MISSING_CASE(info->alternate_aux_channel);
>> > +		return AUX_CH_A;
>> > +	}
>> > +}
>> > +
>> >  static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
>> >  			    enum port port)
>> >  {
>> >  	struct ddi_vbt_port_info *info = &dev_priv->vbt.ddi_port_info[port];
>> >  	enum port p;
>> > +	enum aux_ch aux_ch;
>> > +	bool aux_is_tc;
>> > +	bool phy_is_tc;
>> >  
>> >  	if (!info->alternate_aux_channel)
>> >  		return;
>> > @@ -1571,6 +1598,35 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
>> >  
>> >  		info->supports_dp = false;
>> >  		info->alternate_aux_channel = 0;
>> > +
>> > +		return;
>> > +	}
>> > +
>> > +	aux_ch = intel_bios_port_info_aux_ch(info);
>> > +	/* The AUX CH -> default port is a 1:1 mapping. */
>> > +	aux_is_tc = intel_phy_is_tc(dev_priv,
>> > +				    intel_port_to_phy(dev_priv,
>> > +						      (enum port)aux_ch));
>> > +	phy_is_tc = intel_phy_is_tc(dev_priv,
>> > +				    intel_port_to_phy(dev_priv, port));
>> > +	if (aux_is_tc != phy_is_tc) {
>> > +		/*
>> > +		 * Using an AUX channel which by default belongs to a TypeC
>> > +		 * PHY can't be used for non-TypeC PHYs and vice-versa. The
>> > +		 * reason is that TypeC AUX power wells can only be enabled in
>> > +		 * the current TypeC mode of the PHY and have an effect on power
>> > +		 * management specific to the TypeC subsystem.
>> > +		 */
>> > +		drm_dbg_kms(&dev_priv->drm,
>> > +			    "Port %c on a %s PHY is trying to use the %s AUX CH %c, "
>> > +			    "disabling DP support on this port.\n",
>> > +			    port_name(port),
>> > +			    phy_is_tc ? "TypeC" : "non-TypeC",
>> > +			    aux_is_tc ? "TypeC" : "non-TypeC",
>> > +			    aux_ch_name(aux_ch));
>> > +
>> > +		info->supports_dp = false;
>> > +		info->alternate_aux_channel = 0;
>> >  	}
>> >  }
>> >  
>> > @@ -2595,33 +2651,7 @@ enum aux_ch intel_bios_port_aux_ch(struct drm_i915_private *dev_priv,
>> >  		return aux_ch;
>> >  	}
>> >  
>> > -	switch (info->alternate_aux_channel) {
>> > -	case DP_AUX_A:
>> > -		aux_ch = AUX_CH_A;
>> > -		break;
>> > -	case DP_AUX_B:
>> > -		aux_ch = AUX_CH_B;
>> > -		break;
>> > -	case DP_AUX_C:
>> > -		aux_ch = AUX_CH_C;
>> > -		break;
>> > -	case DP_AUX_D:
>> > -		aux_ch = AUX_CH_D;
>> > -		break;
>> > -	case DP_AUX_E:
>> > -		aux_ch = AUX_CH_E;
>> > -		break;
>> > -	case DP_AUX_F:
>> > -		aux_ch = AUX_CH_F;
>> > -		break;
>> > -	case DP_AUX_G:
>> > -		aux_ch = AUX_CH_G;
>> > -		break;
>> > -	default:
>> > -		MISSING_CASE(info->alternate_aux_channel);
>> > -		aux_ch = AUX_CH_A;
>> > -		break;
>> > -	}
>> > +	aux_ch = intel_bios_port_info_aux_ch(info);
>> >  
>> >  	drm_dbg_kms(&dev_priv->drm, "using AUX %c for port %c (VBT)\n",
>> >  		    aux_ch_name(aux_ch), port_name(port));
>> 
>> -- 
>> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center