Re: [PATCH 1/2] drm/msm/dpu: fail dpu_plane_atomic_check() based on mdp clk limits

[Abhinav Kumar]

On 9/8/2023 4:06 PM, Dmitry Baryshkov wrote:
> On Fri, 8 Sept 2023 at 21:56, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > Currently, dpu_plane_atomic_check() does not check whether the
> > plane can process the image without exceeding the per chipset
> > limits for MDP clock. This leads to underflow issues because the
> > SSPP is not able to complete the processing for the data rate of
> > the display.
> >
> > Fail the dpu_plane_atomic_check() if the SSPP cannot process the
> > image without exceeding the MDP clock limits.
> >
> > Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 15 ++++++++++++---
> >   1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > index 98c1b22e9bca..62dd9f9b4dce 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > @@ -733,9 +733,11 @@ static int dpu_plane_check_inline_rotation(struct dpu_plane *pdpu,
> >   static int dpu_plane_atomic_check_pipe(struct dpu_plane *pdpu,
> >                  struct dpu_sw_pipe *pipe,
> >                  struct dpu_sw_pipe_cfg *pipe_cfg,
> > -               const struct dpu_format *fmt)
> > +               const struct dpu_format *fmt,
> > +               const struct drm_display_mode *mode)
> >   {
> >          uint32_t min_src_size;
> > +       struct dpu_kms *kms = _dpu_plane_get_kms(&pdpu->base);
> >
> >          min_src_size = DPU_FORMAT_IS_YUV(fmt) ? 2 : 1;
> >
> > @@ -774,6 +776,12 @@ static int dpu_plane_atomic_check_pipe(struct dpu_plane *pdpu,
> >                  return -EINVAL;
> >          }
> >
> > +       /* max clk check */
> > +       if (_dpu_plane_calc_clk(mode, pipe_cfg) > kms->perf.max_core_clk_rate) {
> > +               DPU_DEBUG_PLANE(pdpu, "plane exceeds max mdp core clk limits\n");
> > +               return -E2BIG;
> > +       }
> > +
> >          return 0;
> >   }
> >
> > @@ -899,12 +907,13 @@ static int dpu_plane_atomic_check(struct drm_plane *plane,
> >                  r_pipe_cfg->dst_rect.x1 = pipe_cfg->dst_rect.x2;
> >          }
> >
> > -       ret = dpu_plane_atomic_check_pipe(pdpu, pipe, pipe_cfg, fmt);
> > +       ret = dpu_plane_atomic_check_pipe(pdpu, pipe, pipe_cfg, fmt, &crtc_state->mode);
> >          if (ret)
> >                  return ret;
> >
> >          if (r_pipe->sspp) {
> > -               ret = dpu_plane_atomic_check_pipe(pdpu, r_pipe, r_pipe_cfg, fmt);
> > +               ret = dpu_plane_atomic_check_pipe(pdpu, r_pipe, r_pipe_cfg, fmt,
> > +                                                 &crtc_state->mode);
>
> I think this should be adjusted_mode. In the end, according to the
> docs CRTC should be programmed with the adjusted_mode, while the
> state->mode is the mode at the end of the pipeline (if I got it
> correct).
>
> So e.g. if we add DS to the picture, state->mode will be screen
> resolution, while adjusted_moe will be pre-scale resolution, which is
> the one that matters from the bandwidth point of view.

Ack, I should change this to adjusted_mode although today this would be 
the same behavior as dpu_crtc doesn't have a mode_fixup.

so mode = adjusted_mode

https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/drm_atomic_helper.c#L425