Re: [Freedreno] [PATCH 02/11] drm/msm/dpu: use the actual lm maximum width instead of a hardcoded value

[Jeykumar Sankaran]

On 4/19/2023 3:23 PM, Dmitry Baryshkov wrote:
> On 19/04/2023 17:41, Arnaud Vrac wrote:
> > This avoids using two LMs instead of one when the display width is lower
> > than the maximum supported value. For example on MSM8996/MSM8998, the
> > actual maxwidth is 2560, so we would use two LMs for 1280x720 or
> > 1920x1080 resolutions, while one is enough.
> >
> > Signed-off-by: Arnaud Vrac <avrac@xxxxxxxxxx>
>
> While this looks correct (and following what we have in 4.4), later 
> vendor kernels specify the topology explicitly. Probably we should check 
> this with the hw guys, because it might be the following case: even 
> though a single LM can supply the mode, it will spend more power 
> compared to two LMs.
Yes. 2 LM split will allow the HW to run in lower mdp core clock. Can 
you maintain the split_threshold in the hw catalog until per mode 
topology is available?

Jeykumar S
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 10 +++++-----
> >   1 file changed, 5 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 1dc5dbe585723..dd2914726c4f6 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -53,8 +53,6 @@
> >   #define IDLE_SHORT_TIMEOUT    1
> > -#define MAX_HDISPLAY_SPLIT 1080
> > -
> >   /* timeout in frames waiting for frame done */
> >   #define DPU_ENCODER_FRAME_DONE_TIMEOUT_FRAMES 5
> > @@ -568,10 +566,12 @@ static struct msm_display_topology 
> > dpu_encoder_get_topology(
> >        */
> >       if (intf_count == 2)
> >           topology.num_lm = 2;
> > -    else if (!dpu_kms->catalog->caps->has_3d_merge)
> > -        topology.num_lm = 1;
> > +    else if (dpu_kms->catalog->caps->has_3d_merge &&
> > +         dpu_kms->catalog->mixer_count > 0 &&
> > +         mode->hdisplay > dpu_kms->catalog->mixer[0].sblk->maxwidth)
> > +        topology.num_lm = 2;
> >       else
> > -        topology.num_lm = (mode->hdisplay > MAX_HDISPLAY_SPLIT) ? 2 : 1;
> > +        topology.num_lm = 1;
> >       if (crtc_state->ctm)
> >           topology.num_dspp = topology.num_lm;