[Intel-gfx] [PATCH 41/49] drm/i915/bxt: BXT clock divider calculation

[Jesse Barnes]

On 03/17/2015 02:40 AM, Imre Deak wrote:
> From: Satheeshakrishna M <satheeshakrishna.m at intel.com>
> 
> Calculate and cache clock parameters. Follow bspec algorithm for HDMI.
> Use precalculated values for DisplayPort linkrates.
> 
> v2: (imre)
> - rebase against upstream crtc_state change
> - use the existing CHV based helper instead of handrolling the same
> 
> Signed-off-by: Satheeshakrishna M <satheeshakrishna.m at intel.com> (v1)
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 129 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 129 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index bbc3da5..fa4f8f4 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1204,6 +1204,132 @@ skl_ddi_pll_select(struct intel_crtc *intel_crtc,
>  	return true;
>  }
>  
> +/* bxt clock parameters */
> +struct bxt_clk_div {
> +	uint32_t p1;
> +	uint32_t p2;
> +	uint32_t m2_int;
> +	uint32_t m2_frac;
> +	bool m2_frac_en;
> +	uint32_t n;
> +	uint32_t prop_coef;
> +	uint32_t int_coef;
> +	uint32_t gain_ctl;
> +	uint32_t targ_cnt;
> +	uint32_t lanestagger;
> +};
> +
> +/* pre-calculated values for DP linkrates */
> +static struct bxt_clk_div bxt_dp_clk_val[7] = {
> +	/* 162 */ {4, 2, 32, 1677722, 1, 1, 5, 11, 2, 9, 0xd},
> +	/* 270 */ {4, 1, 27,       0, 0, 1, 3,  8, 1, 9, 0xd},
> +	/* 540 */ {2, 1, 27,       0, 0, 1, 3,  8, 1, 9, 0x18},
> +	/* 216 */ {3, 2, 32, 1677722, 1, 1, 5, 11, 2, 9, 0xd},
> +	/* 243 */ {4, 1, 24, 1258291, 1, 1, 5, 11, 2, 9, 0xd},
> +	/* 324 */ {4, 1, 32, 1677722, 1, 1, 5, 11, 2, 9, 0xd},
> +	/* 432 */ {3, 1, 32, 1677722, 1, 1, 5, 11, 2, 9, 0x18}
> +};
> +
> +static bool
> +bxt_ddi_pll_select(struct intel_crtc *intel_crtc,
> +		   struct intel_crtc_state *crtc_state,
> +		   struct intel_encoder *intel_encoder,
> +		   int clock)
> +{
> +	struct intel_shared_dpll *pll;
> +	struct bxt_clk_div clk_div = {0};
> +
> +	if (intel_encoder->type == INTEL_OUTPUT_HDMI) {
> +		intel_clock_t best_clock;
> +
> +		/* Calculate HDMI div */
> +		/*
> +		 * FIXME: tie the following calculation into
> +		 * i9xx_crtc_compute_clock
> +		 */
> +		if (!bxt_find_best_dpll(intel_crtc, clock, &best_clock)) {
> +			DRM_DEBUG_DRIVER("no PLL dividers found for clock %d pipe %c\n",
> +					 clock, pipe_name(intel_crtc->pipe));
> +			return false;
> +		}
> +
> +		clk_div.p1 = best_clock.p1;
> +		clk_div.p2 = best_clock.p2;
> +		WARN_ON(best_clock.m1 != 2);
> +		clk_div.n = best_clock.n;
> +		clk_div.m2_int = best_clock.m2 >> 22;
> +		clk_div.m2_frac = best_clock.m2 & ((1 << 22) - 1);
> +		clk_div.m2_frac_en = clk_div.m2_frac != 0;
> +
> +		/* FIXME: set coef, gain, targcnt based on freq band */
> +		clk_div.prop_coef = 5;
> +		clk_div.int_coef = 11;
> +		clk_div.gain_ctl = 2;
> +		clk_div.targ_cnt = 9;
> +		if (clock > 270000)
> +			clk_div.lanestagger = 0x18;
> +		else if (clock > 135000)
> +			clk_div.lanestagger = 0x0d;
> +		else if (clock > 67000)
> +			clk_div.lanestagger = 0x07;
> +		else if (clock > 33000)
> +			clk_div.lanestagger = 0x04;
> +		else
> +			clk_div.lanestagger = 0x02;
> +	} else if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT ||
> +			intel_encoder->type == INTEL_OUTPUT_EDP) {
> +		struct drm_encoder *encoder = &intel_encoder->base;
> +		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> +
> +		switch (intel_dp->link_bw) {
> +		case DP_LINK_BW_1_62:
> +			clk_div = bxt_dp_clk_val[0];
> +			break;
> +		case DP_LINK_BW_2_7:
> +			clk_div = bxt_dp_clk_val[1];
> +			break;
> +		case DP_LINK_BW_5_4:
> +			clk_div = bxt_dp_clk_val[2];
> +			break;
> +		default:
> +			clk_div = bxt_dp_clk_val[0];
> +			DRM_ERROR("Unknown link rate\n");
> +		}
> +	}
> +
> +	crtc_state->dpll_hw_state.ebb0 =
> +		PORT_PLL_P1(clk_div.p1) | PORT_PLL_P2(clk_div.p2);
> +	crtc_state->dpll_hw_state.pll0 = clk_div.m2_int;
> +	crtc_state->dpll_hw_state.pll1 = PORT_PLL_N(clk_div.n);
> +	crtc_state->dpll_hw_state.pll2 = clk_div.m2_frac;
> +
> +	if (clk_div.m2_frac_en)
> +		crtc_state->dpll_hw_state.pll3 =
> +			PORT_PLL_M2_FRAC_ENABLE;
> +
> +	crtc_state->dpll_hw_state.pll6 =
> +		clk_div.prop_coef | PORT_PLL_INT_COEFF(clk_div.int_coef);
> +	crtc_state->dpll_hw_state.pll6 |=
> +		PORT_PLL_GAIN_CTL(clk_div.gain_ctl);
> +
> +	crtc_state->dpll_hw_state.pll8 = clk_div.targ_cnt;
> +
> +	crtc_state->dpll_hw_state.pcsdw12 =
> +		LANESTAGGER_STRAP_OVRD | clk_div.lanestagger;
> +
> +	pll = intel_get_shared_dpll(intel_crtc, crtc_state);
> +	if (pll == NULL) {
> +		DRM_DEBUG_DRIVER("failed to find PLL for pipe %c\n",
> +			pipe_name(intel_crtc->pipe));
> +		return false;
> +	}
> +
> +	/* shared DPLL id 0 is DPLL A */
> +	crtc_state->ddi_pll_sel = pll->id;
> +
> +	return true;
> +}
> +
>  /*
>   * Tries to find a *shared* PLL for the CRTC and store it in
>   * intel_crtc->ddi_pll_sel.
> @@ -1222,6 +1348,9 @@ bool intel_ddi_pll_select(struct intel_crtc *intel_crtc,
>  	if (IS_SKYLAKE(dev))
>  		return skl_ddi_pll_select(intel_crtc, crtc_state,
>  					  intel_encoder, clock);
> +	else if (IS_BROXTON(dev))
> +		return bxt_ddi_pll_select(intel_crtc, crtc_state,
> +					  intel_encoder, clock);
>  	else
>  		return hsw_ddi_pll_select(intel_crtc, crtc_state,
>  					  intel_encoder, clock);
> 

Should probably have a JIRA on the proper coeff etc values as well.
They're in the bspec, we just have to add the code for the frequency bands.

Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>