Re: [PATCH v2 11/23] drm/i915: Handle the TCCOLD power-down event

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jun 20, 2019 at 05:05:48PM +0300, Imre Deak wrote:
> Based on a recent BSpec update (Index/21750) we must handle the TCCOLD
> event associated with the DP-alt mode. We can detect this event by
> reading an invalid all-1s value from FIA registers.
> 
> After detecting TCCOLD we will:
> - fall back to TBT-alt mode when attempting to switch to DP-alt mode
> - conclude that nothing is connected during live status detection
> - WARN when already in unsafe mode, since then TCCOLD is unexpected
> 
> v2:
> - Use DRM_DEBUG_KMS instead of DRM_DEBUG_DRIVER. (José)

We don't seem to care about the all 1s in icl_tc_phy_status_complete()
and icl_tc_phy_is_in_safe_mode(). Is that OK?

> 
> Cc: José Roberto de Souza <jose.souza@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_tc.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> index a02513814392..fffe4c4a6602 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -29,6 +29,8 @@ u32 intel_tc_port_get_lane_mask(struct intel_digital_port *dig_port)
>  
>  	lane_mask = I915_READ(PORT_TX_DFLEXDPSP);
>  
> +	WARN_ON(lane_mask == -1);
> +
>  	return (lane_mask & DP_LANE_ASSIGNMENT_MASK(tc_port)) >>
>  	       DP_LANE_ASSIGNMENT_SHIFT(tc_port);
>  }
> @@ -89,6 +91,12 @@ static u32 tc_port_live_status_mask(struct intel_digital_port *dig_port)
>  
>  	val = I915_READ(PORT_TX_DFLEXDPSP);
>  
> +	if (val == -1) {

Not sure I like this -1 use. I don't think we typically use it elsewhere
in similar context.

> +		DRM_DEBUG_KMS("Port %s: PHY in TCCOLD, nothing connected\n",
> +			      dig_port->tc_port_name);
> +		return mask;
> +	}
> +
>  	if (val & TC_LIVE_STATE_TBT(tc_port))
>  		mask |= BIT(TC_PORT_TBT_ALT);
>  	if (val & TC_LIVE_STATE_TC(tc_port))
> @@ -113,7 +121,7 @@ static bool icl_tc_phy_status_complete(struct intel_digital_port *dig_port)
>  	       DP_PHY_MODE_STATUS_COMPLETED(tc_port);
>  }
>  
> -static void icl_tc_phy_set_safe_mode(struct intel_digital_port *dig_port,
> +static bool icl_tc_phy_set_safe_mode(struct intel_digital_port *dig_port,
>  				     bool enable)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> @@ -122,6 +130,14 @@ static void icl_tc_phy_set_safe_mode(struct intel_digital_port *dig_port,
>  
>  	val = I915_READ(PORT_TX_DFLEXDPCSSS);
>  
> +	if (val == -1) {
> +		DRM_DEBUG_KMS("Port %s: PHY in TCCOLD, can't set safe-mode to %s\n",
> +			      dig_port->tc_port_name,
> +			      enableddisabled(enable));
> +
> +		return false;
> +	}
> +
>  	val &= ~DP_PHY_MODE_STATUS_NOT_SAFE(tc_port);
>  	if (!enable)
>  		val |= DP_PHY_MODE_STATUS_NOT_SAFE(tc_port);
> @@ -131,6 +147,8 @@ static void icl_tc_phy_set_safe_mode(struct intel_digital_port *dig_port,
>  	if (enable && wait_for(!icl_tc_phy_status_complete(dig_port), 10))
>  		DRM_DEBUG_KMS("Port %s: PHY complete clear timed out\n",
>  			      dig_port->tc_port_name);
> +
> +	return true;
>  }
>  
>  /*
> @@ -169,7 +187,8 @@ static bool icl_tc_phy_connect(struct intel_digital_port *dig_port)
>  		return false;
>  	}
>  
> -	icl_tc_phy_set_safe_mode(dig_port, false);
> +	if (!icl_tc_phy_set_safe_mode(dig_port, false))
> +		return false;
>  
>  	if (dig_port->tc_mode == TC_PORT_LEGACY)
>  		return true;
> -- 
> 2.17.1

-- 
Ville Syrjälä
Intel
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