linux-kernel - Re: [PATCH v3 1/6] drm/msm/dpu: fix video mode DSC for DSI

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Date: Wed, 3 Apr 2024 22:44:06 +0800
From: Jun Nie <jun.nie@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, Vinod Koul <vkoul@...nel.org>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	Jonathan Marek <jonathan@...ek.ca>
Subject: Re: [PATCH v3 1/6] drm/msm/dpu: fix video mode DSC for DSI

Dmitry Baryshkov <dmitry.baryshkov@...aro.org> 于2024年4月3日周三 17:57写道：
>
> On Wed, 3 Apr 2024 at 12:11, Jun Nie <jun.nie@...aro.org> wrote:
> >
> > From: Jonathan Marek <jonathan@...ek.ca>
> >
> > Add necessary DPU timing and control changes for DSC to work with DSI
> > video mode.
> >
> > Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
> > Signed-off-by: Jun Nie <jun.nie@...aro.org>
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 9 +++++++++
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c          | 8 ++++++++
> >  2 files changed, 17 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > index d9e7dbf0499c..c7b009a60b63 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > @@ -115,6 +115,15 @@ static void drm_mode_to_intf_timing_params(
> >                 timing->h_front_porch = timing->h_front_porch >> 1;
> >                 timing->hsync_pulse_width = timing->hsync_pulse_width >> 1;
> >         }
> > +
> > +       /*
> > +        * for DSI, if compression is enabled, then divide the horizonal active
> > +        * timing parameters by compression ratio.
> > +        */
> > +       if (phys_enc->hw_intf->cap->type != INTF_DP && timing->compression_en) {
> > +               timing->width = timing->width / 3; /* XXX: don't assume 3:1 compression ratio */
> > +               timing->xres = timing->width;
> > +       }
> >  }
> >
> >  static u32 get_horizontal_total(const struct dpu_hw_intf_timing_params *timing)
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > index 965692ef7892..079efb48db05 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > @@ -167,6 +167,14 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
> >                 intf_cfg2 |= INTF_CFG2_DATABUS_WIDEN;
> >
> >         data_width = p->width;
> > +       if (p->wide_bus_en && !dp_intf)
> > +               data_width = p->width >> 1;
>
> How is wide_bus relevant to the DSC case?
> Is there a need for the Fixes tag?

48bit bus width should be used when DSC is enabled. Without the
widebus configuration,
a lot dsi error happens as below in DSC case.
[  206.275992] dsi_err_worker: status=4

For the Fixes tag, the previous patch mentioned to enable the widebus
mode for any DSC case. So it is fair to add the tag.
>
> > +
> > +       if (p->compression_en)
> > +               intf_cfg2 |= INTF_CFG2_DCE_DATA_COMPRESS;
> > +
> > +       if (p->compression_en && dp_intf)
> > +               DPU_ERROR("missing adjustments for DSC+DP\n");
> >
> >         hsync_data_start_x = hsync_start_x;
> >         hsync_data_end_x =  hsync_start_x + data_width - 1;
> >
> > --
> > 2.34.1
> >
>
>
> --
> With best wishes
> Dmitry