Re: [PATCH v2 05/13] drm/i915/vrr: Add compute config for DC balance params

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 4/21/2025 9:18 PM, Mitul Golani wrote:
> Add compute config for DC balance params. This will be required
> to calculate correct balance requirement for DMC firmware.
Subject can simply be Compute DC balance parameters.
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_vrr.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index c4fb78d86ab0..383024dc2784 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -16,6 +16,9 @@
>   
>   #define FIXED_POINT_PRECISION		100
>   #define CMRR_PRECISION_TOLERANCE	10
> +#define DCB_CORRECTION_SENSITIVITY	30
> +#define DCB_CORRECTION_AGGRESSIVENESS	1000
> +#define DCB_BLANK_TARGET		50

It would be good to document that whether these values are based on some 
experimentation or some golden values.


>   
>   bool intel_vrr_is_capable(struct intel_connector *connector)
>   {
> @@ -409,6 +412,24 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>   			(crtc_state->hw.adjusted_mode.crtc_vtotal -
>   			 crtc_state->hw.adjusted_mode.vsync_end);
>   	}
> +
> +	if (crtc_state->vrr.dc_balance.enable && HAS_DC_BALANCE(display)) {

Perhaps check for HAS_DC_BALANCE() first.

Regards,

Ankit

> +		crtc_state->vrr.dc_balance.vmax = crtc_state->vrr.vmax;
> +		crtc_state->vrr.dc_balance.vmin = crtc_state->vrr.vmin;
> +		crtc_state->vrr.dc_balance.max_increase =
> +			crtc_state->vrr.vmax - crtc_state->vrr.vmin;
> +		crtc_state->vrr.dc_balance.max_decrease =
> +			crtc_state->vrr.vmax - crtc_state->vrr.vmin;
> +		crtc_state->vrr.dc_balance.guardband =
> +		DIV_ROUND_UP(crtc_state->vrr.dc_balance.vmax * DCB_CORRECTION_SENSITIVITY,
> +			     100);
> +		crtc_state->vrr.dc_balance.slope =
> +			DIV_ROUND_UP(DCB_CORRECTION_AGGRESSIVENESS * 10,
> +				     crtc_state->vrr.dc_balance.guardband);
> +		crtc_state->vrr.dc_balance.vblank_target =
> +		DIV_ROUND_UP((crtc_state->vrr.vmax - crtc_state->vrr.vmin) * DCB_BLANK_TARGET,
> +			     100);
> +	}
>   }
>   
>   void intel_vrr_compute_config_late(struct intel_crtc_state *crtc_state)