Re: [Intel-gfx] [PATCH v2 6/8] drm/i915: Replace hand rolled bxt vco calculation with chv_calc_dpll_params()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 08 Mar 2022, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Use chv_calc_dpll_params() to calculate the BXT DP DPLL VCO
> frequency.
>
> We need to add the m1 divider into bxt_dp_clk_val[] for this to work.
>
> v2: Make the WARN_ON() sensible
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

I admit I didn't check all the computations, but the drm_WARN_ON()
should catch any functional changes AFAICT.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 23 +++++++++++--------
>  1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> index 4b52086aa9e9..b7071da4b7e5 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> @@ -2086,13 +2086,13 @@ static bool bxt_ddi_pll_get_hw_state(struct drm_i915_private *dev_priv,
>  /* pre-calculated values for DP linkrates */
>  static const struct dpll bxt_dp_clk_val[] = {
>  	/* m2 is .22 binary fixed point */
> -	{ .dot = 162000, .p1 = 4, .p2 = 2, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> -	{ .dot = 270000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x6c00000 /* 27.0 */ },
> -	{ .dot = 540000, .p1 = 2, .p2 = 1, .n = 1, .m2 = 0x6c00000 /* 27.0 */ },
> -	{ .dot = 216000, .p1 = 3, .p2 = 2, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> -	{ .dot = 243000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x6133333 /* 24.3 */ },
> -	{ .dot = 324000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> -	{ .dot = 432000, .p1 = 3, .p2 = 1, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> +	{ .dot = 162000, .p1 = 4, .p2 = 2, .n = 1, .m1 = 2, .m2 = 0x819999a /* 32.4 */ },
> +	{ .dot = 270000, .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 /* 27.0 */ },
> +	{ .dot = 540000, .p1 = 2, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 /* 27.0 */ },
> +	{ .dot = 216000, .p1 = 3, .p2 = 2, .n = 1, .m1 = 2, .m2 = 0x819999a /* 32.4 */ },
> +	{ .dot = 243000, .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6133333 /* 24.3 */ },
> +	{ .dot = 324000, .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x819999a /* 32.4 */ },
> +	{ .dot = 432000, .p1 = 3, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x819999a /* 32.4 */ },
>  };
>  
>  static bool
> @@ -2122,18 +2122,21 @@ bxt_ddi_hdmi_pll_dividers(struct intel_crtc_state *crtc_state,
>  static void bxt_ddi_dp_pll_dividers(struct intel_crtc_state *crtc_state,
>  				    struct dpll *clk_div)
>  {
> -	int clock = crtc_state->port_clock;
> +	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
>  	int i;
>  
>  	*clk_div = bxt_dp_clk_val[0];
>  	for (i = 0; i < ARRAY_SIZE(bxt_dp_clk_val); ++i) {
> -		if (bxt_dp_clk_val[i].dot == clock) {
> +		if (crtc_state->port_clock == bxt_dp_clk_val[i].dot) {
>  			*clk_div = bxt_dp_clk_val[i];
>  			break;
>  		}
>  	}
>  
> -	clk_div->vco = clock * 10 / 2 * clk_div->p1 * clk_div->p2;
> +	chv_calc_dpll_params(i915->dpll.ref_clks.nssc, clk_div);
> +
> +	drm_WARN_ON(&i915->drm, clk_div->vco == 0 ||
> +		    clk_div->dot != crtc_state->port_clock);
>  }
>  
>  static bool bxt_ddi_set_dpll_hw_state(struct intel_crtc_state *crtc_state,

-- 
Jani Nikula, Intel Open Source Graphics Center