[Intel-gfx] [PATCH v3 2/6] drm/i915: Remove the link rate and lane count loop in compute config

[Jani Nikula]

On Fri, 16 Sep 2016, Manasi Navare <manasi.d.navare at intel.com> 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.

As I wrote in reply to patch 1/6, this is not a DP spec requirement. The
link policy maker can freely choose the link parameters as long as the
sink supports them.

BR,
Jani.


>
> v3:
> * Add Debug print if requested mode cannot be supported
> during modeset (Dhinakaran Pandiyan)
> v2:
> * Removed the loop since we use max values of clock
> and lane count (Dhinakaran Pandiyan)
>
> Signed-off-by: Manasi Navare <manasi.d.navare at 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 d81c67cb..65b4559 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1644,23 +1644,17 @@ 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);
> +		clock = max_clock;
> +		lane_count = max_lane_count;
> +		link_clock = common_rates[clock];
> +		link_avail = intel_dp_max_data_rate(link_clock,
> +						    lane_count);
>  
> -		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;
> -				}
> -			}
> -		}
> +		if (mode_rate <= link_avail)
> +			goto found;
>  	}
>  
> +	DRM_DEBUG_KMS("Requested Mode Rate not supported\n");
>  	return false;
>  
>  found:

-- 
Jani Nikula, Intel Open Source Technology Center