Re: [PATCH 4/4] drm/i915: Extract drm_dp_atomic_find_vcpi_slots cycle to separate function

["Govindapillai, Vinod" <vinod.govindapillai@intel.com>]

Hi Stan,

I wonder if it is better if you reorder the 3 and 4 patches in this - move this 4/4 before the 3rd
one and modify the 3rd one accordingly.

Also, instead of getting rid of limits, keep limits and populate the limits according to dsc or
normal dp_mst. What do you think?

BR
vinod


On Mon, 2022-08-29 at 12:58 +0300, Stanislav Lisovskiy wrote:
> We are using almost same code to loop through bpps while calling
> drm_dp_atomic_find_vcpi_slots - lets remove this duplication by
> introducing a new function intel_dp_mst_find_vcpi_slots_for_bpp
> 
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 88 +++++++++++----------
>  1 file changed, 46 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 94d7e7f84c51..2a524816dbfd 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -44,10 +44,14 @@
>  #include "intel_hotplug.h"
>  #include "skl_scaler.h"
>  
> -static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
> -                                           struct intel_crtc_state *crtc_state,
> -                                           struct drm_connector_state *conn_state,
> -                                           struct link_config_limits *limits)
> +static int intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder,
> +                                               struct intel_crtc_state *crtc_state,
> +                                               int max_bpp,
> +                                               int min_bpp,
> +                                               struct link_config_limits *limits,
> +                                               struct drm_connector_state *conn_state,
> +                                               int step,
> +                                               bool dsc)
>  {
>         struct drm_atomic_state *state = crtc_state->uapi.state;
>         struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
> @@ -58,7 +62,6 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>         struct drm_i915_private *i915 = to_i915(connector->base.dev);
>         const struct drm_display_mode *adjusted_mode =
>                 &crtc_state->hw.adjusted_mode;
> -       bool constant_n = drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_CONSTANT_N);
>         int bpp, slots = -EINVAL;
>         int ret = 0;
>  
> @@ -71,19 +74,21 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>  
>         // TODO: Handle pbn_div changes by adding a new MST helper
>         if (!mst_state->pbn_div) {
> -               mst_state->pbn_div = drm_dp_get_vc_payload_bw(&intel_dp->mst_mgr,
> -                                                             limits->max_rate,
> -                                                             limits->max_lane_count);
> +               mst_state->pbn_div = !dsc ? drm_dp_get_vc_payload_bw(&intel_dp->mst_mgr,
> +                                                                    crtc_state->port_clock,
> +                                                                    crtc_state->lane_count) : 0;
>         }
>  
> -       for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) {
> +       for (bpp = max_bpp; bpp >= min_bpp; bpp -= step) {
>                 crtc_state->pipe_bpp = bpp;
>  
>                 crtc_state->pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock,
> -                                                      crtc_state->pipe_bpp,
> -                                                      false);
> +                                                      dsc ? bpp << 4 : crtc_state->pipe_bpp,
> +                                                      dsc);
> +
>                 slots = drm_dp_atomic_find_time_slots(state, &intel_dp->mst_mgr,
> -                                                     connector->port, crtc_state->pbn);
> +                                                     connector->port,
> +                                                     crtc_state->pbn);
>                 if (slots == -EDEADLK)
>                         return slots;
>                 if (slots >= 0) {
> @@ -101,11 +106,32 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>         if (ret && slots >= 0)
>                 slots = ret;
>  
> -       if (slots < 0) {
> +       if (slots < 0)
>                 drm_dbg_kms(&i915->drm, "failed finding vcpi slots:%d\n",
>                             slots);
> +
> +       return slots;
> +}
> +
> +
> +static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
> +                                           struct intel_crtc_state *crtc_state,
> +                                           struct drm_connector_state *conn_state,
> +                                           struct link_config_limits *limits)
> +{
> +       const struct drm_display_mode *adjusted_mode =
> +               &crtc_state->hw.adjusted_mode;
> +       struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
> +       struct intel_dp *intel_dp = &intel_mst->primary->dp;
> +       bool constant_n = drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_CONSTANT_N);
> +       int slots = -EINVAL;
> +
> +       slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state, limits->max_bpp,
> +                                                    limits->min_bpp, limits,
> +                                                    conn_state, 2 * 3, false);
> +
> +       if (slots < 0)
>                 return slots;
> -       }
>  
>         intel_link_compute_m_n(crtc_state->pipe_bpp,
>                                crtc_state->lane_count,
> @@ -123,25 +149,21 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder
> *encoder,
>                                                 struct drm_connector_state *conn_state,
>                                                 struct link_config_limits *limits)
>  {
> -       struct drm_atomic_state *state = crtc_state->uapi.state;
> -       struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
> -       struct intel_dp *intel_dp = &intel_mst->primary->dp;
>         struct intel_connector *connector =
>                 to_intel_connector(conn_state->connector);
> +       struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
> +       struct intel_dp *intel_dp = &intel_mst->primary->dp;
>         struct drm_i915_private *i915 = to_i915(connector->base.dev);
>         const struct drm_display_mode *adjusted_mode =
>                 &crtc_state->hw.adjusted_mode;
>         bool constant_n = drm_dp_has_quirk(&intel_dp->desc,
>                                            DP_DPCD_QUIRK_CONSTANT_N);
> -       int bpp, slots = -EINVAL;
> +       int slots = -EINVAL;
>         int i, num_bpc;
>         u8 dsc_bpc[3] = {0};
>         int min_bpp, max_bpp;
>         u8 dsc_max_bpc;
>  
> -       crtc_state->lane_count = limits->max_lane_count;
> -       crtc_state->port_clock = limits->max_rate;
> -
>         /* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
>         if (DISPLAY_VER(i915) >= 12)
>                 dsc_max_bpc = min_t(u8, 12, conn_state->max_requested_bpc);
> @@ -162,29 +184,11 @@ static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder
> *encoder,
>         drm_dbg_kms(&i915->drm, "DSC Sink supported min bpp %d max bpp %d\n",
>                     min_bpp, max_bpp);
>  
> -       for (bpp = max_bpp; bpp >= min_bpp; bpp -= 2 * 3) {
> -               crtc_state->pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock,
> -                                                      bpp << 4,
> -                                                      true);
> +       slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state, max_bpp, min_bpp,
> +                                                    limits, conn_state, 2 * 3, true);
>  
> -               slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
> -                                                     connector->port,
> -                                                     crtc_state->pbn, 0);
> -
> -               drm_dbg_kms(&i915->drm, "Trying bpp %d got %d pbn %d slots\n",
> -                           bpp, crtc_state->pbn, slots);
> -
> -               if (slots == -EDEADLK)
> -                       return slots;
> -               if (slots >= 0)
> -                       break;
> -       }
> -
> -       if (slots < 0) {
> -               drm_dbg_kms(&i915->drm, "failed finding vcpi slots:%d\n",
> -                           slots);
> +       if (slots < 0)
>                 return slots;
> -       }
>  
>         intel_link_compute_m_n(crtc_state->pipe_bpp,
>                                crtc_state->lane_count,