Re: [Intel-gfx] [PATCH v2 4/8] drm/i915: Store the m2 divider as a whole in bxt_clk_div

[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>
>
> Get rid of the pointless m2 int vs. frac split in bxt_clk_div
> and just store the whole divider as one.
>
> v2: Document the full divider as a proper decimal number
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

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

> ---
>  drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 27 +++++++++----------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> index 2a88c6fa1f34..ae3c07cc2eaa 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> @@ -2088,8 +2088,7 @@ struct bxt_clk_div {
>  	int clock;
>  	u32 p1;
>  	u32 p2;
> -	u32 m2_int;
> -	u32 m2_frac;
> +	u32 m2;
>  	u32 n;
>  
>  	int vco;
> @@ -2097,13 +2096,14 @@ struct bxt_clk_div {
>  
>  /* pre-calculated values for DP linkrates */
>  static const struct bxt_clk_div bxt_dp_clk_val[] = {
> -	{ .clock = 162000, .p1 = 4, .p2 = 2, .m2_int = 32, .m2_frac = 1677722, .n = 1, },
> -	{ .clock = 270000, .p1 = 4, .p2 = 1, .m2_int = 27, .m2_frac =       0, .n = 1, },
> -	{ .clock = 540000, .p1 = 2, .p2 = 1, .m2_int = 27, .m2_frac =       0, .n = 1, },
> -	{ .clock = 216000, .p1 = 3, .p2 = 2, .m2_int = 32, .m2_frac = 1677722, .n = 1, },
> -	{ .clock = 243000, .p1 = 4, .p2 = 1, .m2_int = 24, .m2_frac = 1258291, .n = 1, },
> -	{ .clock = 324000, .p1 = 4, .p2 = 1, .m2_int = 32, .m2_frac = 1677722, .n = 1, },
> -	{ .clock = 432000, .p1 = 3, .p2 = 1, .m2_int = 32, .m2_frac = 1677722, .n = 1, },
> +	/* m2 is .22 binary fixed point */
> +	{ .clock = 162000, .p1 = 4, .p2 = 2, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> +	{ .clock = 270000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x6c00000 /* 27.0 */ },
> +	{ .clock = 540000, .p1 = 2, .p2 = 1, .n = 1, .m2 = 0x6c00000 /* 27.0 */ },
> +	{ .clock = 216000, .p1 = 3, .p2 = 2, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> +	{ .clock = 243000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x6133333 /* 24.3 */ },
> +	{ .clock = 324000, .p1 = 4, .p2 = 1, .n = 1, .m2 = 0x819999a /* 32.4 */ },
> +	{ .clock = 432000, .p1 = 3, .p2 = 1, .n = 1, .m2 = 0x819999a /* 32.4 */ },
>  };
>  
>  static bool
> @@ -2130,8 +2130,7 @@ bxt_ddi_hdmi_pll_dividers(struct intel_crtc_state *crtc_state,
>  	clk_div->p2 = best_clock.p2;
>  	drm_WARN_ON(&i915->drm, 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 = best_clock.m2;
>  
>  	clk_div->vco = best_clock.vco;
>  
> @@ -2200,11 +2199,11 @@ static bool bxt_ddi_set_dpll_hw_state(struct intel_crtc_state *crtc_state,
>  		lanestagger = 0x02;
>  
>  	dpll_hw_state->ebb0 = PORT_PLL_P1(clk_div->p1) | PORT_PLL_P2(clk_div->p2);
> -	dpll_hw_state->pll0 = PORT_PLL_M2_INT(clk_div->m2_int);
> +	dpll_hw_state->pll0 = PORT_PLL_M2_INT(clk_div->m2 >> 22);
>  	dpll_hw_state->pll1 = PORT_PLL_N(clk_div->n);
> -	dpll_hw_state->pll2 = PORT_PLL_M2_FRAC(clk_div->m2_frac);
> +	dpll_hw_state->pll2 = PORT_PLL_M2_FRAC(clk_div->m2 & 0x3fffff);
>  
> -	if (clk_div->m2_frac)
> +	if (clk_div->m2 & 0x3fffff)
>  		dpll_hw_state->pll3 = PORT_PLL_M2_FRAC_ENABLE;
>  
>  	dpll_hw_state->pll6 = PORT_PLL_PROP_COEFF(prop_coef) |

-- 
Jani Nikula, Intel Open Source Graphics Center