Re: [PATCH 4/7] drm/i915/cnl: Fix wrpll math for higher freqs.

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Nov 14, 2017 at 08:00:31PM +0000, Ville Syrjälä wrote:
> On Tue, Nov 14, 2017 at 11:47:56AM -0800, Rodrigo Vivi wrote:
> > Spec describe all values in MHz. We handle our
> > clocks in KHz. This includes the best_dco_centrality that was
> > forgot in the same unity as spec. Consequently we couldn't
> > get a good divider for high frequenies. Hence HDMI 2.0 wasn't
> > working.
> > 
> > This patch also replaces the use of "* KHz(1)" with the values
> > directly on KHz to avoid future confusion.
> > 
> > Cc: Shashank Sharma <shashank.sharma@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>
> > ---
> >  drivers/gpu/drm/i915/intel_dpll_mgr.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > index fba969cbda37..53f650f56148 100644
> > --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> > @@ -2201,8 +2201,8 @@ cnl_ddi_calculate_wrpll(int clock,
> >  			struct skl_wrpll_params *wrpll_params)
> >  {
> >  	u32 afe_clock = clock * 5;
> > -	u32 dco_min = 7998 * KHz(1);
> > -	u32 dco_max = 10000 * KHz(1);
> > +	u32 dco_min = 7998000;
> > +	u32 dco_max = 10000000;
> >  	u32 dco_mid = (dco_min + dco_max) / 2;
> >  	static const int dividers[] = {  2,  4,  6,  8, 10, 12,  14,  16,
> >  					 18, 20, 24, 28, 30, 32,  36,  40,
> > @@ -2211,7 +2211,7 @@ cnl_ddi_calculate_wrpll(int clock,
> >  					 84, 88, 90, 92, 96, 98, 100, 102,
> >  					  3,  5,  7,  9, 15, 21 };
> >  	u32 dco, best_dco = 0, dco_centrality = 0;
> > -	u32 best_dco_centrality = 999999;
> > +	u32 best_dco_centrality = 999999000;
> 
> UINT_MAX, -1, or ~0 maybe?

yeap, I considered the max macros, but I didn't want to deviate
from spec...

> 
> >  	int d, best_div = 0, pdiv = 0, qdiv = 0, kdiv = 0;
> >  
> >  	for (d = 0; d < ARRAY_SIZE(dividers); d++) {
> > -- 
> > 2.13.6
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
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