Re: [PATCH] drm/i915/ehl: Add support for DPLL4 (v3)

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

On Fri, Apr 05, 2019 at 10:59:53AM -0700, Vivek Kasireddy wrote:
> This patch adds support for DPLL4 on EHL that include the
> following restrictions:
> 
> - DPLL4 cannot be used with DDIA (combo port A internal eDP usage).
>   DPLL4 can be used with other DDIs, including DDID
>   (combo port A external usage).
> 
> - DPLL4 cannot be enabled when DC5 or DC6 are enabled.
> 
> - The DPLL4 enable, lock, power enabled, and power state are connected
>   to the MGPLL1_ENABLE register.
> 
> v2: (suggestions from Bob Paauwe)
> - Rework ehl_get_dpll() function to call intel_find_shared_dpll() and
>   iterate twice: once for Combo plls and once for MG plls.
> 
> - Use MG pll funcs for DPLL4 instead of creating new ones and modify
>   mg_pll_enable to include the restrictions for EHL.
> 
> v3: Fix compilation error
> 
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> Reviewed-by: Bob Paauwe <bob.j.paauwe@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dpll_mgr.c | 60 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> index e01c057ce50b..c3f0b9720c54 100644
> --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> @@ -2870,6 +2870,56 @@ icl_get_dpll(struct intel_crtc_state *crtc_state,
>  	return pll;
>  }
>  
> +static struct intel_shared_dpll *
> +ehl_get_dpll(struct intel_crtc_state *crtc_state,
> +	     struct intel_encoder *encoder)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
> +	struct intel_shared_dpll *pll;
> +	enum port port = encoder->port;
> +	enum intel_dpll_id min, max;
> +	bool ret;
> +
> +	if (!intel_port_is_combophy(dev_priv, port)) {
> +		MISSING_CASE(port);
> +		return NULL;
> +	}
> +
> +	min = DPLL_ID_ICL_DPLL0;
> +	max = DPLL_ID_ICL_DPLL1;
> +	ret = icl_calc_dpll_state(crtc_state, encoder);
> +	if (ret) {
> +		pll = intel_find_shared_dpll(crtc_state, min, max);
> +		if (pll) {
> +			intel_reference_shared_dpll(pll, crtc_state);
> +			return pll;
> +		}
> +	} else {
> +		DRM_DEBUG_KMS("Could not calculate PLL state.\n");
> +	}
> +
> +	if (encoder->type == INTEL_OUTPUT_EDP) {
> +		DRM_DEBUG_KMS("Cannot use DPLL4 with EDP.\n");
> +		return NULL;
> +	}
> +
> +	min = max = DPLL_ID_ICL_MGPLL1;
> +	ret = icl_calc_mg_pll_state(crtc_state);
> +	if (!ret) {
> +		DRM_DEBUG_KMS("Could not calculate PLL state.\n");
> +		return NULL;
> +	}
> +
> +	pll = intel_find_shared_dpll(crtc_state, min, max);
> +	if (!pll) {
> +		DRM_DEBUG_KMS("No PLL selected\n");
> +		return NULL;
> +	}
> +
> +	intel_reference_shared_dpll(pll, crtc_state);
> +	return pll;
> +}
> +
>  static bool mg_pll_get_hw_state(struct drm_i915_private *dev_priv,
>  				struct intel_shared_dpll *pll,
>  				struct intel_dpll_hw_state *hw_state)
> @@ -3115,6 +3165,13 @@ static void mg_pll_enable(struct drm_i915_private *dev_priv,
>  	i915_reg_t enable_reg =
>  		MG_PLL_ENABLE(icl_pll_id_to_tc_port(pll->info->id));
>  
> +	if (IS_ELKHARTLAKE(dev_priv) &&
> +	   (I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5 ||
> +	    I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6)) {
> +		DRM_ERROR("Cant enable DPLL4 when DC5 or DC6 are enabled\n");
> +		return;
> +	}

This looks like dead code, or we messed up earlier already (in which
case it should just be some kind of assert IMO).

Also what is this EHL thing anyway? I can't even find it in the spec.

> +
>  	icl_pll_power_enable(dev_priv, pll, enable_reg);
>  
>  	icl_mg_pll_write(dev_priv, pll);
> @@ -3249,12 +3306,13 @@ static const struct intel_dpll_mgr icl_pll_mgr = {
>  static const struct dpll_info ehl_plls[] = {
>  	{ "DPLL 0", &combo_pll_funcs, DPLL_ID_ICL_DPLL0, 0 },
>  	{ "DPLL 1", &combo_pll_funcs, DPLL_ID_ICL_DPLL1, 0 },
> +	{ "DPLL 4", &mg_pll_funcs, DPLL_ID_ICL_MGPLL1,0 },
>  	{ },
>  };
>  
>  static const struct intel_dpll_mgr ehl_pll_mgr = {
>  	.dpll_info = ehl_plls,
> -	.get_dpll = icl_get_dpll,
> +	.get_dpll = ehl_get_dpll,
>  	.dump_hw_state = icl_dump_hw_state,
>  };
>  
> -- 
> 2.14.5
> 
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-- 
Ville Syrjälä
Intel
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