Re: [PATCH 08/16] drm/msm/dpu: add support to allocate CDM from RM

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

On 8/30/2023 5:06 PM, Dmitry Baryshkov wrote:
> On Thu, 31 Aug 2023 at 01:50, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > Even though there is usually only one CDM block, it can be
> > used by either HDMI, DisplayPort OR Writeback interfaces.
> >
> > Hence its allocation needs to be tracked properly by the
> > resource manager to ensure appropriate availability of the
> > block.
>
> It almost feels like an overkill, as up to now there is at most one CDM block.

Yes but even that one CDM block can be used by any connector. So as we 
discussed on IRC, this just implements the FCFS and we need RM to be the 
manager of that one block.

> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c |  2 +-
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h |  1 +
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h     |  1 +
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c      | 45 +++++++++++++++++++--
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h      |  4 +-
> >   5 files changed, 48 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index 6cf6597148fd..582680804016 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -663,7 +663,7 @@ static int dpu_encoder_virt_atomic_check(
> >
> >                  if (!crtc_state->active_changed || crtc_state->enable)
> >                          ret = dpu_rm_reserve(&dpu_kms->rm, global_state,
> > -                                       drm_enc, crtc_state, topology);
> > +                                       drm_enc, crtc_state, topology, false);
> >          }
> >
> >          trace_dpu_enc_atomic_check_flags(DRMID(drm_enc), adj_mode->flags);
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> > index 34f943102499..07f75f295844 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> > @@ -98,6 +98,7 @@ enum dpu_hw_blk_type {
> >          DPU_HW_BLK_DSPP,
> >          DPU_HW_BLK_MERGE_3D,
> >          DPU_HW_BLK_DSC,
> > +       DPU_HW_BLK_CDM,
> >          DPU_HW_BLK_MAX,
> >   };
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > index b6f53ca6e962..61aa58643fda 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > @@ -136,6 +136,7 @@ struct dpu_global_state {
> >          uint32_t ctl_to_enc_id[CTL_MAX - CTL_0];
> >          uint32_t dspp_to_enc_id[DSPP_MAX - DSPP_0];
> >          uint32_t dsc_to_enc_id[DSC_MAX - DSC_0];
> > +       uint32_t cdm_to_enc_id;
> >   };
> >
> >   struct dpu_global_state
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> > index 7b6444a3fcb1..e7d4beb4661e 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> > @@ -29,10 +29,12 @@ static inline bool reserved_by_other(uint32_t *res_map, int idx,
> >   /**
> >    * struct dpu_rm_requirements - Reservation requirements parameter bundle
> >    * @topology:  selected topology for the display
> > + * @needs_cdm: whether the display needs a CDM block for the current mode
> >    * @hw_res:       Hardware resources required as reported by the encoders
> >    */
> >   struct dpu_rm_requirements {
> >          struct msm_display_topology topology;
> > +       bool needs_cdm;
> >   };
> >
> >   int dpu_rm_destroy(struct dpu_rm *rm)
> > @@ -505,6 +507,26 @@ static int _dpu_rm_reserve_dsc(struct dpu_rm *rm,
> >          return 0;
> >   }
> >
> > +static int _dpu_rm_reserve_cdm(struct dpu_rm *rm,
> > +                              struct dpu_global_state *global_state,
> > +                              struct drm_encoder *enc)
> > +{
> > +       /* try allocating only one CDM block */
> > +       if (!rm->cdm_blk) {
> > +               DPU_ERROR("CDM block does not exist\n");
> > +               return -EIO;
> > +       }
> > +
> > +       if (global_state->cdm_to_enc_id) {
> > +               DPU_ERROR("CDM_0 is already allocated\n");
> > +               return -EIO;
> > +       }
> > +
> > +       global_state->cdm_to_enc_id = enc->base.id;
> > +
> > +       return 0;
> > +}
> > +
> >   static int _dpu_rm_make_reservation(
> >                  struct dpu_rm *rm,
> >                  struct dpu_global_state *global_state,
> > @@ -530,15 +552,25 @@ static int _dpu_rm_make_reservation(
> >          if (ret)
> >                  return ret;
> >
> > +       if (reqs->needs_cdm) {
> > +               ret = _dpu_rm_reserve_cdm(rm, global_state, enc);
> > +               if (ret) {
> > +                       DPU_ERROR("unable to find CDM blk\n");
> > +                       return ret;
> > +               }
> > +       }
> > +
> >          return ret;
> >   }
> >
> >   static int _dpu_rm_populate_requirements(
> >                  struct drm_encoder *enc,
> >                  struct dpu_rm_requirements *reqs,
> > -               struct msm_display_topology req_topology)
> > +               struct msm_display_topology req_topology,
> > +               bool needs_cdm)
>
> Push it to the topology, please. It is a part of the topology at some
> point of view.

hmmm ... ok with a pinch of salt as we somewhat deviate from the true 
topology definition that topology is just how lm, dsc and intf blocks 
are used. it was not intended to hold cdm.

> >   {
> >          reqs->topology = req_topology;
> > +       reqs->needs_cdm = needs_cdm;
> >
> >          DRM_DEBUG_KMS("num_lm: %d num_dsc: %d num_intf: %d\n",
> >                        reqs->topology.num_lm, reqs->topology.num_dsc,
> > @@ -571,6 +603,7 @@ void dpu_rm_release(struct dpu_global_state *global_state,
> >                  ARRAY_SIZE(global_state->dsc_to_enc_id), enc->base.id);
> >          _dpu_rm_clear_mapping(global_state->dspp_to_enc_id,
> >                  ARRAY_SIZE(global_state->dspp_to_enc_id), enc->base.id);
> > +       _dpu_rm_clear_mapping(&global_state->cdm_to_enc_id, 1, enc->base.id);
> >   }
> >
> >   int dpu_rm_reserve(
> > @@ -578,7 +611,8 @@ int dpu_rm_reserve(
> >                  struct dpu_global_state *global_state,
> >                  struct drm_encoder *enc,
> >                  struct drm_crtc_state *crtc_state,
> > -               struct msm_display_topology topology)
> > +               struct msm_display_topology topology,
> > +               bool needs_cdm)
> >   {
> >          struct dpu_rm_requirements reqs;
> >          int ret;
> > @@ -595,7 +629,7 @@ int dpu_rm_reserve(
> >          DRM_DEBUG_KMS("reserving hw for enc %d crtc %d\n",
> >                        enc->base.id, crtc_state->crtc->base.id);
> >
> > -       ret = _dpu_rm_populate_requirements(enc, &reqs, topology);
> > +       ret = _dpu_rm_populate_requirements(enc, &reqs, topology, needs_cdm);
> >          if (ret) {
> >                  DPU_ERROR("failed to populate hw requirements\n");
> >                  return ret;
> > @@ -644,6 +678,11 @@ int dpu_rm_get_assigned_resources(struct dpu_rm *rm,
> >                  hw_to_enc_id = global_state->dsc_to_enc_id;
> >                  max_blks = ARRAY_SIZE(rm->dsc_blks);
> >                  break;
> > +       case DPU_HW_BLK_CDM:
> > +               hw_blks = &rm->cdm_blk;
> > +               hw_to_enc_id = &global_state->cdm_to_enc_id;
> > +               max_blks = 1;
> > +               break;
> >          default:
> >                  DPU_ERROR("blk type %d not managed by rm\n", type);
> >                  return 0;
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> > index 29b221491926..74262d3cb6c3 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h
> > @@ -69,13 +69,15 @@ int dpu_rm_destroy(struct dpu_rm *rm);
> >    * @drm_enc: DRM Encoder handle
> >    * @crtc_state: Proposed Atomic DRM CRTC State handle
> >    * @topology: Pointer to topology info for the display
> > + * @needs_cdm: bool to indicate whether current encoder needs CDM
> >    * @Return: 0 on Success otherwise -ERROR
> >    */
> >   int dpu_rm_reserve(struct dpu_rm *rm,
> >                  struct dpu_global_state *global_state,
> >                  struct drm_encoder *drm_enc,
> >                  struct drm_crtc_state *crtc_state,
> > -               struct msm_display_topology topology);
> > +               struct msm_display_topology topology,
> > +               bool needs_cdm);
> >
> >   /**
> >    * dpu_rm_reserve - Given the encoder for the display chain, release any
> > --
> > 2.40.1