[Intel-gfx] [PATCH 10/12] drm/i915: Allow rate_to_index() to return non-exact matches

[Ville Syrjälä]

On Fri, Jul 29, 2016 at 11:35:27AM +0200, Daniel Vetter wrote:
> On Thu, Jul 28, 2016 at 05:50:46PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Let's make rate_to_index() return the highest rate available that's
> > less than or equal to the rate requested by the caller. The function
> > can then be used to filter out rates higher than a certain maximum
> > rate.
> > 
> > Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
> > Cc: Jim Bride <jim.bride at linux.intel.com>
> > Cc: Manasi D Navare <manasi.d.navare at intel.com>
> > Cc: Durgadoss R <durgadoss.r at intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Not sure what this will be used for, couldn't figure it out looking at
> later patches?

Ah, forgot to mention that part. It seemed like there was a hunk in the
upfront link training patch that could use this, rather than hand
rolling yet another way of looking through the rate array.

> -Daneil
> 
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 40cae6202160..08d95352ffd6 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1431,10 +1431,13 @@ static int rate_to_index(int find, const int *rates)
> >  	int i = 0;
> >  
> >  	for (i = 0; i < DP_MAX_SUPPORTED_RATES; ++i)
> > -		if (find == rates[i])
> > +		if (find < rates[i])
> >  			break;
> >  
> > -	return i;
> > +	if (WARN_ON(i == 0))
> > +		return 0;
> > +
> > +	return i - 1;
> >  }
> >  
> >  int
> > -- 
> > 2.7.4
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC