linux-kernel - Re: [PATCH v17 1/4] drm/msm/dpu: Extract plane splitting into a dedicated function

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Message-ID: <CABymUCOSNtWoNRAxTheqkLxJM8kWYwQoR7=HJdKdsJwfC9NVLg@mail.gmail.com>
Date: Wed, 21 Jan 2026 17:47:12 +0800
From: Jun Nie <jun.nie@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Abhinav Kumar <abhinav.kumar@...ux.dev>, Dmitry Baryshkov <lumag@...nel.org>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Rob Clark <robin.clark@....qualcomm.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v17 1/4] drm/msm/dpu: Extract plane splitting into a
 dedicated function

Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com> 于2026年1月21日周三 17:29写道：
>
> On Wed, Jan 21, 2026 at 04:01:50PM +0800, Jun Nie wrote:
> > dpu_plane_atomic_check_nosspp() currently handles both plane
> > validation and plane splitting. For better simplicity and to
> > facilitate future refactoring, move the splitting logic into
> > its own dedicated function.
> >
> > Signed-off-by: Jun Nie <jun.nie@...aro.org>
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 51 ++++++++++++++++++++++---------
> >  1 file changed, 36 insertions(+), 15 deletions(-)
> >
> > @@ -879,6 +866,34 @@ static int dpu_plane_atomic_check_nosspp(struct drm_plane *plane,
> >               if (pstate->layout.plane_pitch[i] > DPU_SSPP_MAX_PITCH_SIZE)
> >                       return -E2BIG;
> >
> > +     pstate->needs_qos_remap = drm_atomic_crtc_needs_modeset(crtc_state);
> > +
> > +     return 0;
> > +}
> > +
> > +static int dpu_plane_split(struct drm_plane *plane,
> > +                        struct drm_plane_state *new_plane_state,
> > +                        const struct drm_crtc_state *crtc_state)
> > +{
> > +     struct dpu_plane *pdpu = to_dpu_plane(plane);
> > +     struct dpu_kms *kms = _dpu_plane_get_kms(&pdpu->base);
> > +     u64 max_mdp_clk_rate = kms->perf.max_core_clk_rate;
> > +     struct dpu_plane_state *pstate = to_dpu_plane_state(new_plane_state);
> > +     struct dpu_sw_pipe_cfg *pipe_cfg;
> > +     struct dpu_sw_pipe_cfg *r_pipe_cfg;
> > +     uint32_t max_linewidth;
> > +
> > +     if (!new_plane_state->visible)
> > +             return 0;
> > +
> > +     /* move the assignment here, to ease handling to another pairs later */
> > +     pipe_cfg = &pstate->pipe_cfg[0];
> > +     r_pipe_cfg = &pstate->pipe_cfg[1];
> > +     /* state->src is 16.16, src_rect is not */
> > +     drm_rect_fp_to_int(&pipe_cfg->src_rect, &new_plane_state->src);
> > +
> > +     pipe_cfg->dst_rect = new_plane_state->dst;
> > +
> >       max_linewidth = pdpu->catalog->caps->max_linewidth;
> >
> >       drm_rect_rotate(&pipe_cfg->src_rect,
> > @@ -910,8 +925,6 @@ static int dpu_plane_atomic_check_nosspp(struct drm_plane *plane,
> >                                   new_plane_state->fb->width, new_plane_state->fb->height,
> >                                   new_plane_state->rotation);
> >
> > -     pstate->needs_qos_remap = drm_atomic_crtc_needs_modeset(crtc_state);
> > -
> >       return 0;
> >  }
> >
> > @@ -1129,6 +1142,10 @@ static int dpu_plane_atomic_check(struct drm_plane *plane,
> >       if (ret)
> >               return ret;
> >
> > +     ret = dpu_plane_split(plane, new_plane_state, crtc_state);
> > +     if (ret)
> > +             return ret;
> > +
> >       if (!new_plane_state->visible)
> >               return 0;
> >
> > @@ -1169,6 +1186,10 @@ static int dpu_plane_virtual_atomic_check(struct drm_plane *plane,
> >       if (ret)
> >               return ret;
> >
> > +     ret = dpu_plane_split(plane, plane_state, crtc_state);
> > +     if (ret)
> > +             return ret;
>
> Why can't it be moved after !visible check? It's the first check in the
> function code.

Surely it can be moved after !visible check and it is a better place. Placing
 it just after dpu_plane_atomic_check_nosspp() is because
it is splitted from it. And it does not matter actually, because
dpu_plane_split() is moved to the deferred part
dpu_plane_virtual_assign_resources()
in the later patch. So that topology information is ready at that stage.

>
> > +
> >       if (!plane_state->visible) {
> >               /*
> >                * resources are freed by dpu_crtc_assign_plane_resources(),
> >
> > --
> > 2.43.0
> >
>
> --
> With best wishes
> Dmitry