Re: [PATCH v2 12/14] drm/i915: Remove the link rate and lane count loop in compute config

[Manasi Navare <manasi.d.navare@intel.com>]

On Mon, Sep 12, 2016 at 06:14:00PM -0700, Pandiyan, Dhinakaran wrote:
> On Thu, 2016-09-08 at 13:02 -0700, Manasi Navare wrote:
> > While configuring the pipe during modeset, it should use
> > max clock and max lane count and reduce the bpp until
> > the requested mode rate is less than or equal to
> > available link BW.
> > This is required to pass DP Compliance.
> > 
> > v2:
> > * Removed the loop since we use max values of clock
> > and lane count (Dhinakaran Pandiyan)
> > 
> > Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 22 ++++++++--------------
> >  1 file changed, 8 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 1378116..60c8857 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1567,20 +1567,14 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >  	for (; bpp >= 6*3; bpp -= 2*3) {
> >  		mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
> >  						   bpp);
> > -
> > -		for (clock = min_clock; clock <= max_clock; clock++) {
> > -			for (lane_count = min_lane_count;
> > -				lane_count <= max_lane_count;
> > -				lane_count <<= 1) {
> > -
> > -				link_clock = common_rates[clock];
> > -				link_avail = intel_dp_max_data_rate(link_clock,
> > -								    lane_count);
> > -
> > -				if (mode_rate <= link_avail) {
> > -					goto found;
> > -				}
> > -			}
> > +		clock = max_clock;
> > +		lane_count = max_lane_count;
> 
> Do we still need lane_count? We can eliminate it if it's always going to
> be max_lane_count. 
> 
>

This is just to follow the paradigm and use lane count and link rate here
while setting up the pipe config.

 
> > +		link_clock = common_rates[clock];
> 
> Same here for link_clock.
> 
> > +		link_avail = intel_dp_max_data_rate(link_clock,
> > +						    lane_count);
> > +
> > +		if (mode_rate <= link_avail) {
> > +			goto found;
> 
> Print KMS debug if we cannot satisfy the mode_rate at the max DP link
> rate?
>

Agree, but I am going to add it outside the bpp loop. You should see 
a new patch soon.

Manasi 
> >  		}
> >  	}
> >  
> 
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