On Thu, 2025-11-27 at 19:49 +0200, Imre Deak wrote:
> A DSC compressed stream requires FEC (except for eDP), which has a BW
> overhead on non-UHBR links that must be accounted for explicitly. Do
> that during computing the required BW.
> 
> Note that the overhead doesn't need to be accounted for on UHBR links
> where FEC is always enabled and so the corresponding overhead is part of
> the channel coding efficiency instead (i.e. the overhead is part of the
> available vs. the required BW).
> 
> Signed-off-by: Imre Deak <[email protected]>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4044bdbceaef5..55be648283b19 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2085,12 +2085,16 @@ static int dsc_compute_link_config(struct intel_dp 
> *intel_dp,
>                               if (ret)
>                                       continue;
>                       } else {
> +                             unsigned long bw_overhead_flags =
> +                                     pipe_config->fec_enable ? 
> DRM_DP_BW_OVERHEAD_FEC : 0;
> +
>                               if (!is_bw_sufficient_for_dsc_config(intel_dp,
>                                                                    link_rate, 
> lane_count,
>                                                                    
> adjusted_mode->crtc_clock,
>                                                                    
> adjusted_mode->hdisplay,
>                                                                    
> pipe_config->dsc.slice_count,
> -                                                                  
> dsc_bpp_x16, 0))
> +                                                                  
> dsc_bpp_x16,
> +                                                                  
> bw_overhead_flags))
>                                       continue;
>                       }
>  

Reviewed-by: Luca Coelho <[email protected]>

--
Cheers,
Luca.

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