[Intel-gfx] [PATCH 3/5] drm/i915/icl: Cross check the combo PLL WRPLL parameters wrt. hard-coded PLL freqs

[Imre Deak]

When selecting the WRPLL dividers for a given port clock/PLL freq, the
hard-coded PLL freq in a table entry can be calculated using the rest of
parameters in the same entry. Cross-check if the hard coded values match
what we calculate with the formula.

Signed-off-by: Imre Deak <imre.d...@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 26 ++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c 
b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
index e3370c8dccc8..ded2b2dfe319 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
@@ -3002,6 +3002,30 @@ static const struct skl_wrpll_params 
tgl_tbt_pll_38_4MHz_values = {
        .pdiv = 0, .kdiv = 0, .qdiv_mode = 0, .qdiv_ratio = 0,
 };
 
+static int icl_wrpll_ref_clock(struct drm_i915_private *i915);
+
+static bool icl_dp_combo_pll_clock_match(struct drm_i915_private *i915, int 
clock,
+                                        const struct icl_combo_pll_params *p)
+{
+       int ref_clock = icl_wrpll_ref_clock(i915);
+       int pll_freq;
+       u32 pdiv;
+       u32 qdiv;
+       u32 kdiv;
+
+       cnl_wrpll_decode_divs(&p->wrpll, &pdiv, &qdiv, &kdiv);
+
+       pll_freq = skl_wrpll_calc_freq(ref_clock,
+                                      p->wrpll.dco_integer, 
p->wrpll.dco_fraction,
+                                      pdiv, qdiv, kdiv);
+       drm_WARN_ON(&i915->drm, pll_freq != p->clock);
+
+       if (clock == pll_freq)
+               return true;
+
+       return false;
+}
+
 static bool icl_calc_dp_combo_pll(struct intel_crtc_state *crtc_state,
                                  struct skl_wrpll_params *pll_params)
 {
@@ -3014,7 +3038,7 @@ static bool icl_calc_dp_combo_pll(struct intel_crtc_state 
*crtc_state,
        int i;
 
        for (i = 0; i < ARRAY_SIZE(icl_dp_combo_pll_24MHz_values); i++) {
-               if (clock == params[i].clock) {
+               if (icl_dp_combo_pll_clock_match(dev_priv, clock, &params[i])) {
                        *pll_params = params[i].wrpll;
                        return true;
                }
-- 
2.25.1

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