[Intel-gfx] [PATCH 6/7] drm/i915/cnl: Write dco_fraction calculation as spec.

[Rodrigo Vivi]

I confess I never fully understood that previous calculation,
so maybe this is cannot be called a "fix". But let's follow
the math that is written on Spec so we have get more confident
this is what hardware expect.

Cc: Mika Kahola <mika.kahola at intel.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
Cc: James Ausmus <james.ausmus at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/i915/intel_dpll_mgr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index bd608f7f2399..ee690d2f6e54 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2190,8 +2190,8 @@ static void cnl_wrpll_params_populate(struct skl_wrpll_params *params,
 	params->qdiv_mode = (qdiv == 1) ? 0 : 1;
 
 	params->dco_integer = div_u64(dco_freq, ref_freq);
-	params->dco_fraction = div_u64((div_u64((uint64_t)dco_freq<<15, (uint64_t)ref_freq) -
-					((uint64_t)params->dco_integer<<15)) * 0x8000, 0x8000);
+	params->dco_fraction = (DIV_ROUND_UP_ULL(dco_freq, ref_freq) -
+				params->dco_integer) * (1 << 15);
 }
 
 static bool
-- 
2.13.6