Re: [PATCH v1 4/5] drm/msm/dpu: calculate DSC encoder parameters dynamically

[Kuogee Hsieh]

On 4/20/2023 5:27 PM, Dmitry Baryshkov wrote:
> On 21/04/2023 02:25, Kuogee Hsieh wrote:
> > During DSC preparation, add run time calculation to figure out what
> > usage modes, split mode and merge mode, is going to be setup.
> >
> > Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 56 
> > ++++++++++++++++-------------
> >   1 file changed, 32 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index 2fdacf1..5677728 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -529,17 +529,9 @@ void dpu_encoder_helper_split_config(
> >   bool dpu_encoder_use_dsc_merge(struct drm_encoder *drm_enc)
> >   {
> >       struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
> > -    int i, intf_count = 0, num_dsc = 0;
> > +    struct msm_display_topology *topology = &dpu_enc->topology;
> >   -    for (i = 0; i < MAX_PHYS_ENCODERS_PER_VIRTUAL; i++)
> > -        if (dpu_enc->phys_encs[i])
> > -            intf_count++;
> > -
> > -    /* See dpu_encoder_get_topology, we only support 2:2:1 topology */
> > -    if (dpu_enc->dsc)
> > -        num_dsc = 2;
> > -
> > -    return (num_dsc > 0) && (num_dsc > intf_count);
> > +    return (topology->num_dsc > topology->num_intf);
> >   }
> >     static void dpu_encoder_get_topology(
> > @@ -1861,41 +1853,57 @@ static void dpu_encoder_prep_dsc(struct 
> > dpu_encoder_virt *dpu_enc,
> >       struct dpu_encoder_phys *enc_master = dpu_enc->cur_master;
> >       struct dpu_hw_dsc *hw_dsc[MAX_CHANNELS_PER_ENC];
> >       struct dpu_hw_pingpong *hw_pp[MAX_CHANNELS_PER_ENC];
> > +    struct msm_display_topology *topology = &dpu_enc->topology;
> >       int this_frame_slices;
> >       int intf_ip_w, enc_ip_w;
> > -    int dsc_common_mode;
> > +    int dsc_common_mode = 0;
> >       int pic_width;
> >       u32 initial_lines;
> > +    int num_dsc, num_intf;
> >       int i;
> >         for (i = 0; i < MAX_CHANNELS_PER_ENC; i++) {
> >           hw_pp[i] = dpu_enc->hw_pp[i];
> >           hw_dsc[i] = dpu_enc->hw_dsc[i];
> > -
> > -        if (!hw_pp[i] || !hw_dsc[i]) {
> > -            DPU_ERROR_ENC(dpu_enc, "invalid params for DSC\n");
> > -            return;
> > -        }
Why?

MAX_CHANNELS_PER_ENC == 2

This works for dsi since it use 2 dsc encoder.

Since DP only use one dsc encoder, this will cause it return at loop 2 
without execute dpu_encoder_dsc_pipe_cfg().

> >       }
> >   -    dsc_common_mode = 0;
> > +    num_dsc = topology->num_dsc;
> > +    num_intf = topology->num_intf;
> > +
> >       pic_width = dsc->pic_width;
> >   -    dsc_common_mode = DSC_MODE_MULTIPLEX | DSC_MODE_SPLIT_PANEL;
> >       if (enc_master->intf_mode == INTF_MODE_VIDEO)
> >           dsc_common_mode |= DSC_MODE_VIDEO;
> >   +    /*
> > +     * If this encoder is driving more than one DSC encoder, they
> > +     * operate in tandem, same pic dimension needs to be used by
> > +     * each of them.(pp-split is assumed to be not supported)
> > +     *
> > +     */
> > +
> >       this_frame_slices = pic_width / dsc->slice_width;
> >       intf_ip_w = this_frame_slices * dsc->slice_width;
> > +    enc_ip_w = intf_ip_w;
> > +
> > +    intf_ip_w /= num_intf;
> > +
> > +    if (num_dsc > 1)
> > +        dsc_common_mode |= DSC_MODE_SPLIT_PANEL;
> > +
> > +    if (dpu_encoder_use_dsc_merge(&dpu_enc->base)) {
> > +        dsc_common_mode |= DSC_MODE_MULTIPLEX;
> > +        /*
> > +         * in dsc merge case: when using 2 encoders for the same
> > +         * stream, no. of slices need to be same on both the
> > +         * encoders.
> > +         */
> > +        enc_ip_w = intf_ip_w / 2;
>
> So do you want to get enc_ip_w / 2 or enc_ip_w / num_intf / 2 here?
enc_ip_w / num_intf / 2
> > +    }
> >   -    /*
> > -     * dsc merge case: when using 2 encoders for the same stream,
> > -     * no. of slices need to be same on both the encoders.
> > -     */
> > -    enc_ip_w = intf_ip_w / 2;
> >       initial_lines = dpu_encoder_dsc_initial_line_calc(dsc, enc_ip_w);
> >   -    for (i = 0; i < MAX_CHANNELS_PER_ENC; i++)
> > +    for (i = 0; i < num_dsc; i++)
> >           dpu_encoder_dsc_pipe_cfg(dpu_enc, hw_dsc[i], hw_pp[i], dsc,
> >                       dsc_common_mode, initial_lines);
> >   }