On Wed, 25 Nov 2020 at 15:33, Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx> wrote: > > In case of panels with low vertical back porch, the prefill bw > requirement will be high as we will have less time(vbp+pw) to > fetch and fill the hw latency buffers before start of first line > in active period. > > For ex: > Say hw_latency_line_buffers = 24, and if blanking vbp+pw = 10 > Here we need to fetch 24 lines of data in 10 line times. > This will increase the bw to the ratio of linebuffers to blanking. > > DPU hw can also fetch data during vertical front porch provided > interface prefetch is enabled. Use vfp in the prefill calculation > as dpu driver enables prefetch if the blanking is not sufficient > to fill the latency lines. Tested on Xiaomi Poco F1 (sdm845). Tested-by: Amit Pundir <amit.pundir@xxxxxxxxxx> > > Signed-off-by: Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx> > --- > drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c > index 7ea90d2..315b999 100644 > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c > @@ -151,7 +151,7 @@ static void _dpu_plane_calc_bw(struct drm_plane *plane, > u64 plane_bw; > u32 hw_latency_lines; > u64 scale_factor; > - int vbp, vpw; > + int vbp, vpw, vfp; > > pstate = to_dpu_plane_state(plane->state); > mode = &plane->state->crtc->mode; > @@ -164,6 +164,7 @@ static void _dpu_plane_calc_bw(struct drm_plane *plane, > fps = drm_mode_vrefresh(mode); > vbp = mode->vtotal - mode->vsync_end; > vpw = mode->vsync_end - mode->vsync_start; > + vfp = mode->vsync_start - mode->vdisplay; > hw_latency_lines = dpu_kms->catalog->perf.min_prefill_lines; > scale_factor = src_height > dst_height ? > mult_frac(src_height, 1, dst_height) : 1; > @@ -176,7 +177,13 @@ static void _dpu_plane_calc_bw(struct drm_plane *plane, > src_width * hw_latency_lines * fps * fmt->bpp * > scale_factor * mode->vtotal; > > - do_div(plane_prefill_bw, (vbp+vpw)); > + if ((vbp+vpw) > hw_latency_lines) > + do_div(plane_prefill_bw, (vbp+vpw)); > + else if ((vbp+vpw+vfp) < hw_latency_lines) > + do_div(plane_prefill_bw, (vbp+vpw+vfp)); > + else > + do_div(plane_prefill_bw, hw_latency_lines); > + > > pstate->plane_fetch_bw = max(plane_bw, plane_prefill_bw); > } > -- > 2.7.4 >
