Re: [PATCH] drm/i915: Only poll DW3_A when init DDI PHY for ports B and C.

[Imre Deak <imre.deak@intel.com>]

On to, 2016-11-10 at 17:03 -0800, Rodrigo Vivi wrote:
> According to Bspec we need to
> "Poll for PORT_REF_DW3_A grc_done == 1b"
> only on ports B and C initialization sequence when
> copying rcomp from port A.
> 
> So let's follow the spec and only poll for that case
> and not on every port A initialization.
> 
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Ander Conselvan de Oliveira 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

The current code isn't against the spec, we just wait for the
calibration to complete earlier. This way we also wait in case only
port A is enabled which is imo safer to do before a subsequent modeset
on port A. But yes, the spec suggests the HW will handle the wait for
this - only port A - case internally, so we can move the wait later to
reduce somewhat the init time:

Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_dpio_phy.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dpio_phy.c b/drivers/gpu/drm/i915/intel_dpio_phy.c
> index 7a8e82d..277b1aa 100644
> --- a/drivers/gpu/drm/i915/intel_dpio_phy.c
> +++ b/drivers/gpu/drm/i915/intel_dpio_phy.c
> @@ -367,6 +367,9 @@ static void _bxt_ddi_phy_init(struct drm_i915_private *dev_priv,
>  
>  	if (phy_info->rcomp_phy != -1) {
>  		uint32_t grc_code;
> +
> +		bxt_phy_wait_grc_done(dev_priv, phy_info->rcomp_phy);
> +
>  		/*
>  		 * PHY0 isn't connected to an RCOMP resistor so copy over
>  		 * the corresponding calibrated value from PHY1, and disable
> @@ -387,10 +390,6 @@ static void _bxt_ddi_phy_init(struct drm_i915_private *dev_priv,
>  	val = I915_READ(BXT_PHY_CTL_FAMILY(phy));
>  	val |= COMMON_RESET_DIS;
>  	I915_WRITE(BXT_PHY_CTL_FAMILY(phy), val);
> -
> -	if (phy_info->rcomp_phy == -1)
> -		bxt_phy_wait_grc_done(dev_priv, phy);
> -
>  }
>  
>  void bxt_ddi_phy_uninit(struct drm_i915_private *dev_priv, enum dpio_phy phy)
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