Re: [PATCH 13/16] drm/msm/dpu: reserve cdm blocks for writeback in case of YUV output

[Abhinav Kumar]

On 8/30/2023 5:23 PM, Dmitry Baryshkov wrote:
> On Thu, 31 Aug 2023 at 01:50, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > Reserve CDM blocks for writeback if the format of the output fb
> > is YUV. At the moment, the reservation is done only for writeback
> > but can easily be extended by relaxing the checks once other
> > interfaces are ready to output YUV.
> >
> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 35 ++++++++++++++++++++-
> >   1 file changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index 1b1e07292a9e..7a3d179bdfba 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -16,6 +16,7 @@
> >   #include <drm/drm_crtc.h>
> >   #include <drm/drm_file.h>
> >   #include <drm/drm_probe_helper.h>
> > +#include <drm/drm_framebuffer.h>
> >
> >   #include "msm_drv.h"
> >   #include "dpu_kms.h"
> > @@ -615,9 +616,11 @@ static int dpu_encoder_virt_atomic_check(
> >          struct drm_display_mode *adj_mode;
> >          struct msm_display_topology topology;
> >          struct dpu_global_state *global_state;
> > +       struct drm_framebuffer *fb;
> >          struct drm_dsc_config *dsc;
> >          int i = 0;
> >          int ret = 0;
> > +       bool needs_cdm = false;
> >
> >          if (!drm_enc || !crtc_state || !conn_state) {
> >                  DPU_ERROR("invalid arg(s), drm_enc %d, crtc/conn state %d/%d\n",
> > @@ -655,6 +658,22 @@ static int dpu_encoder_virt_atomic_check(
> >
> >          topology = dpu_encoder_get_topology(dpu_enc, dpu_kms, adj_mode, crtc_state, dsc);
> >
> > +       /*
> > +        * Use CDM only for writeback at the moment as other interfaces cannot handle it.
> > +        * if writeback itself cannot handle cdm for some reason it will fail in its atomic_check()
> > +        * earlier.
> > +        */
> > +       if (dpu_enc->disp_info.intf_type == INTF_WB && conn_state->writeback_job) {
> > +               fb = conn_state->writeback_job->fb;
> > +
> > +               if (fb && DPU_FORMAT_IS_YUV(to_dpu_format(msm_framebuffer_format(fb))))
> > +                       needs_cdm = true;
> > +               if (needs_cdm && !dpu_enc->cur_master->hw_cdm)
> > +                       crtc_state->mode_changed = true;
> > +               else if (!needs_cdm && dpu_enc->cur_master->hw_cdm)
> > +                       crtc_state->mode_changed = true;
> > +       }
>
> What would be the (estimated) check for DP?

Originally we were planning a lot more but now we are going to start 
with the mode being drm_mode_is_420_only and use CDM for that.

> > +
> >          /*
> >           * Release and Allocate resources on every modeset
> >           * Dont allocate when active is false.
> > @@ -664,7 +683,7 @@ 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, false);
> > +                                       drm_enc, crtc_state, topology, needs_cdm);
> >          }
> >
> >          trace_dpu_enc_atomic_check_flags(DRMID(drm_enc), adj_mode->flags);
> > @@ -1126,6 +1145,20 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
> >
> >          dpu_enc->dsc_mask = dsc_mask;
> >
> > +       if (dpu_enc->disp_info.intf_type == INTF_WB && conn_state->writeback_job) {
> > +               struct dpu_hw_blk *hw_cdm = NULL;
> > +               struct drm_framebuffer *fb;
> > +
> > +               fb = conn_state->writeback_job->fb;
> > +
> > +               if (fb && DPU_FORMAT_IS_YUV(to_dpu_format(msm_framebuffer_format(fb)))) {
>
> You can drop all fb-related conditions here. If we have CDM, we know
> that we asked for it. If we do not, it's because we do not need it.

hmmm .... let me do some testing with this and if it works I will make 
this change as well. Thanks.

> > +                       dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
> > +                                                     drm_enc->base.id, DPU_HW_BLK_CDM,
> > +                                                     &hw_cdm, 1);
> > +               }
> > +               dpu_enc->cur_master->hw_cdm = hw_cdm ? to_dpu_hw_cdm(hw_cdm) : NULL;
> > +       }
> > +
> >          cstate = to_dpu_crtc_state(crtc_state);
> >
> >          for (i = 0; i < num_lm; i++) {
> > --
> > 2.40.1