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| author | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2017-11-15 10:42:57 -0800 |
|---|---|---|
| committer | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2017-11-16 09:45:39 -0800 |
| commit | 8a00678a096445716861d2c0bd2a7007ad373f4d (patch) | |
| tree | 0be8018d6ba0ff743498673753222399c1926dd3 /drivers/gpu/drm/i915/intel_dpll_mgr.c | |
| parent | cacf6fe7c6c4ac9e748f41d0de4293b2aea5ae07 (diff) | |
| download | blackbird-obmc-linux-8a00678a096445716861d2c0bd2a7007ad373f4d.tar.gz blackbird-obmc-linux-8a00678a096445716861d2c0bd2a7007ad373f4d.zip | |
drm/i915/cnl: Simplify dco_fraction calculation.
I confess I never fully understood that previous calculation,
so this is not a "fix". But let's simplify this math
so poor brains like mine can read and make some sense of
it in the future.
v2: Don't follow the spec since that gives invalid
values and it is also confusing. This Ville's
version is much simpler.
v3: Use u64 cast instead of declaring a u64 dco. (Ville).
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Mika Kahola <mika.kahola@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: James Ausmus <james.ausmus@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171115184257.8633-1-rodrigo.vivi@intel.com
Diffstat (limited to 'drivers/gpu/drm/i915/intel_dpll_mgr.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_dpll_mgr.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c index 361b7102b602..51c5ae4e9116 100644 --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c @@ -2153,6 +2153,8 @@ static void cnl_wrpll_params_populate(struct skl_wrpll_params *params, u32 dco_freq, u32 ref_freq, int pdiv, int qdiv, int kdiv) { + u32 dco; + switch (kdiv) { case 1: params->kdiv = 1; @@ -2189,9 +2191,10 @@ static void cnl_wrpll_params_populate(struct skl_wrpll_params *params, params->qdiv_ratio = qdiv; 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); + dco = div_u64((u64)dco_freq << 15, ref_freq); + + params->dco_integer = dco >> 15; + params->dco_fraction = dco & 0x7fff; } static bool |
