linux-kernel - Re: [PATCH v3 5/6] drm/display: Add slice_per

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Message-ID: <CABymUCODHQ=bobQNhttY-RqLDjEGf75yAm2YD--ZnfXjAtzNMw@mail.gmail.com>
Date: Mon, 8 Apr 2024 17:58:29 +0800
From: Jun Nie <jun.nie@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Konrad Dybcio <konrad.dybcio@...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
Subject: Re: [PATCH v3 5/6] drm/display: Add slice_per_pkt for dsc

Dmitry Baryshkov <dmitry.baryshkov@...aro.org> 于2024年4月3日周三 17:41写道：
>
> On Wed, 3 Apr 2024 at 12:11, Jun Nie <jun.nie@...aro.org> wrote:
> >
> > Add variable for slice number of a DSC compression bit stream packet.
> > Its value shall be specified in panel driver, or default value can be set
> > in display controller driver if panel driver does not set it.
>
> This is not a part of the standard. Please justify it.

Right, I read the standard but did not find any details of packet description.
Looks like msm silicon support tuning of number of slice packing per downstream
code.
The slice_per_pkt can be set in the downstream msm device tree. And I test the
values 1 and 2 on vtdr6130 panel and both work. So I guess this is related to
performance or something like that. I will have more test with different panel
to check the impact.
drivers/gpu/drm/panel/panel-raydium-rm692e5.c also mentions to pass new value
to slice_per_pkt.

Hi Konrad,
Do you remember why value 2 is TODO for slice_per_pkt for panel rm692e5?

>
> >
> > Signed-off-by: Jun Nie <jun.nie@...aro.org>
> > ---
> >  include/drm/display/drm_dsc.h | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/include/drm/display/drm_dsc.h b/include/drm/display/drm_dsc.h
> > index bc90273d06a6..4fac0a2746ae 100644
> > --- a/include/drm/display/drm_dsc.h
> > +++ b/include/drm/display/drm_dsc.h
> > @@ -82,6 +82,10 @@ struct drm_dsc_config {
> >          * @bits_per_component: Bits per component to code (8/10/12)
> >          */
> >         u8 bits_per_component;
> > +       /**
> > +        * @slice_per_pkt: slice number per DSC bit stream packet
> > +        */
> > +       u8 slice_per_pkt;
> >         /**
> >          * @convert_rgb:
> >          * Flag to indicate if RGB - YCoCg conversion is needed
> >
> > --
> > 2.34.1
> >
>
>
> --
> With best wishes
> Dmitry