[Intel-gfx] [PATCH v2 07/11] drm/i915/dp_mst: Calculate the BW overhead in intel_dp_mst_find_vcpi_slots_for_bpp()

[Murthy, Arun R]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Imre
> Deak
> Sent: Thursday, November 16, 2023 6:49 PM
> To: intel-gfx at lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH v2 07/11] drm/i915/dp_mst: Calculate the BW
> overhead in intel_dp_mst_find_vcpi_slots_for_bpp()
> 
> The next patch will calculate the PBN value directly from the pixel data rate and
> the BW allocation overhead, not requiring the data, link M/N and TU values for
> this. To prepare for that move the calculation of BW overheads from
> intel_dp_mst_compute_m_n() to intel_dp_mst_find_vcpi_slots_for_bpp().
> 
> While at it store link_bpp in a .4 fixed point format.
> 
> Signed-off-by: Imre Deak <imre.deak at intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy at intel.com>

Thanks and Regards,
Arun R Murthy
-------------------
> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 27 ++++++++++++++-------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index e5d6b811c22ef..a5ddd1781969d 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -108,15 +108,12 @@ static int intel_dp_mst_bw_overhead(const struct
> intel_crtc_state *crtc_state,
> 
>  static void intel_dp_mst_compute_m_n(const struct intel_crtc_state
> *crtc_state,
>  				     const struct intel_connector *connector,
> -				     bool ssc, bool dsc,
> +				     int overhead,
>  				     int bpp_x16,
>  				     struct intel_link_m_n *m_n)
>  {
>  	const struct drm_display_mode *adjusted_mode =
>  		&crtc_state->hw.adjusted_mode;
> -	int overhead = intel_dp_mst_bw_overhead(crtc_state,
> -						connector,
> -						ssc, dsc, bpp_x16);
> 
>  	intel_link_compute_m_n(bpp_x16, crtc_state->lane_count,
>  			       adjusted_mode->crtc_clock,
> @@ -171,7 +168,9 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct
> intel_encoder *encoder,
> 
>  	for (bpp = max_bpp; bpp >= min_bpp; bpp -= step) {
>  		struct intel_link_m_n remote_m_n;
> -		int link_bpp;
> +		int local_bw_overhead;
> +		int remote_bw_overhead;
> +		int link_bpp_x16;
> 
>  		drm_dbg_kms(&i915->drm, "Trying bpp %d\n", bpp);
> 
> @@ -179,12 +178,22 @@ static int
> intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder,
>  		if (ret)
>  			continue;
> 
> -		link_bpp = dsc ? bpp :
> -			intel_dp_output_bpp(crtc_state->output_format, bpp);
> +		link_bpp_x16 = to_bpp_x16(dsc ? bpp :
> +					  intel_dp_output_bpp(crtc_state-
> >output_format, bpp));
> 
> -		intel_dp_mst_compute_m_n(crtc_state, connector, false, dsc,
> to_bpp_x16(link_bpp),
> +		local_bw_overhead = intel_dp_mst_bw_overhead(crtc_state,
> connector,
> +							     false, dsc,
> link_bpp_x16);
> +		remote_bw_overhead = intel_dp_mst_bw_overhead(crtc_state,
> connector,
> +							      true, dsc,
> link_bpp_x16);
> +
> +		intel_dp_mst_compute_m_n(crtc_state, connector,
> +					 local_bw_overhead,
> +					 link_bpp_x16,
>  					 &crtc_state->dp_m_n);
> -		intel_dp_mst_compute_m_n(crtc_state, connector, true, dsc,
> to_bpp_x16(link_bpp),
> +
> +		intel_dp_mst_compute_m_n(crtc_state, connector,
> +					 remote_bw_overhead,
> +					 link_bpp_x16,
>  					 &remote_m_n);
> 
>  		/*
> --
> 2.39.2