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From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date:   Thu, 7 Jul 2022 18:33:02 +0300
Message-ID: <CAA8EJpoYj_-bY8CSPdE=mBkZbnffgUXX+LzEXKWHQ3yhS4GmvA@mail.gmail.com>
Subject: Re: [PATCH v4 1/7] drm/msm/disp/dpu1: clear dpu_assign_crtc and get
 crtc from drm_enc instead of dpu_enc
To:     Vinod Polimera <vpolimer@qti.qualcomm.com>
Cc:     "Vinod Polimera (QUIC)" <quic_vpolimer@quicinc.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        "freedreno@lists.freedesktop.org" <freedreno@lists.freedesktop.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "robdclark@gmail.com" <robdclark@gmail.com>,
        "dianders@chromium.org" <dianders@chromium.org>,
        "swboyd@chromium.org" <swboyd@chromium.org>,
        "Kalyan Thota (QUIC)" <quic_kalyant@quicinc.com>,
        "Kuogee Hsieh (QUIC)" <quic_khsieh@quicinc.com>,
        "Vishnuvardhan Prodduturi (QUIC)" <quic_vproddut@quicinc.com>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "Aravind Venkateswaran (QUIC)" <quic_aravindh@quicinc.com>,
        "Abhinav Kumar (QUIC)" <quic_abhinavk@quicinc.com>,
        "Sankeerth Billakanti (QUIC)" <quic_sbillaka@quicinc.com>
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On Thu, 7 Jul 2022 at 17:39, Vinod Polimera <vpolimer@qti.qualcomm.com> wrote:
>
> > NAK. Quoting the documentation:
> >
> > only really meaningful for non-atomic drivers. Atomic drivers should
> > instead check &drm_connector_state.crtc.
> >
> > Please adjust according to the documentation.
>    drm_enc gets the crtc info already from new connector state as part of drm_atomic_helper_update_legacy_modeset_state.
>    So drm_enc->crtc will be valid as we access it as part of modeset enable/disable.
>                          ```connector->encoder->crtc = new_conn_state->crtc;```.

drm_atomic_helper_update_legacy_modeset_state():

 * Since these updates are not synchronized with lockings, only code paths
 * called from &drm_mode_config_helper_funcs.atomic_commit_tail can look at the
 * legacy state filled out by this helper. Defacto this means this helper and
 * the legacy state pointers are only really useful for transitioning an
 * existing driver to the atomic world.

So please change the code to use drm_connector_state.crtc.

Dixi.

>
> Thanks,
> Vinod P.
>
> > -----Original Message-----
> > From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > Sent: Wednesday, July 6, 2022 12:34 AM
> > To: Vinod Polimera (QUIC) <quic_vpolimer@quicinc.com>; dri-
> > devel@lists.freedesktop.org; linux-arm-msm@vger.kernel.org;
> > freedreno@lists.freedesktop.org; devicetree@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org; robdclark@gmail.com;
> > dianders@chromium.org; swboyd@chromium.org; Kalyan Thota (QUIC)
> > <quic_kalyant@quicinc.com>; Kuogee Hsieh (QUIC)
> > <quic_khsieh@quicinc.com>; Vishnuvardhan Prodduturi (QUIC)
> > <quic_vproddut@quicinc.com>; bjorn.andersson@linaro.org; Aravind
> > Venkateswaran (QUIC) <quic_aravindh@quicinc.com>; Abhinav Kumar
> > (QUIC) <quic_abhinavk@quicinc.com>; Sankeerth Billakanti (QUIC)
> > <quic_sbillaka@quicinc.com>
> > Subject: Re: [PATCH v4 1/7] drm/msm/disp/dpu1: clear dpu_assign_crtc and
> > get crtc from drm_enc instead of dpu_enc
> >
> > WARNING: This email originated from outside of Qualcomm. Please be wary
> > of any links or attachments, and do not enable macros.
> >
> > On 05/07/2022 20:00, Vinod Polimera wrote:
> > > Update crtc retrieval from dpu_enc to drm_enc, since new links get set
> > > as part of the update legacy mode set. The dpu_enc->crtc cache is no
> > > more needed, hence cleaning it as part of this change.
> >
> > NAK. Quoting the documentation:
> >
> > only really meaningful for non-atomic drivers. Atomic drivers should
> > instead check &drm_connector_state.crtc.
> >
> > Please adjust according to the documentation.
> > >
> > > Signed-off-by: Vinod Polimera <quic_vpolimer@quicinc.com>
> > > ---
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    |  4 ----
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 18 +++---------------
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  8 --------
> > >   3 files changed, 3 insertions(+), 27 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > index b56f777..f91e3d1 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > @@ -972,7 +972,6 @@ static void dpu_crtc_disable(struct drm_crtc *crtc,
> > >                */
> > >               if (dpu_encoder_get_intf_mode(encoder) == INTF_MODE_VIDEO)
> > >                       release_bandwidth = true;
> > > -             dpu_encoder_assign_crtc(encoder, NULL);
> > >       }
> > >
> > >       /* wait for frame_event_done completion */
> > > @@ -1042,9 +1041,6 @@ static void dpu_crtc_enable(struct drm_crtc *crtc,
> > >       trace_dpu_crtc_enable(DRMID(crtc), true, dpu_crtc);
> > >       dpu_crtc->enabled = true;
> > >
> > > -     drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state-
> > >encoder_mask)
> > > -             dpu_encoder_assign_crtc(encoder, crtc);
> > > -
> > >       /* Enable/restore vblank irq handling */
> > >       drm_crtc_vblank_on(crtc);
> > >   }
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > index 52516eb..5629c0b 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > @@ -1254,8 +1254,8 @@ static void dpu_encoder_vblank_callback(struct
> > drm_encoder *drm_enc,
> > >       dpu_enc = to_dpu_encoder_virt(drm_enc);
> > >
> > >       spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> > > -     if (dpu_enc->crtc)
> > > -             dpu_crtc_vblank_callback(dpu_enc->crtc);
> > > +     if (drm_enc->crtc)
> > > +             dpu_crtc_vblank_callback(drm_enc->crtc);
> > >       spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > >
> > >       atomic_inc(&phy_enc->vsync_cnt);
> > > @@ -1280,18 +1280,6 @@ static void
> > dpu_encoder_underrun_callback(struct drm_encoder *drm_enc,
> > >       DPU_ATRACE_END("encoder_underrun_callback");
> > >   }
> > >
> > > -void dpu_encoder_assign_crtc(struct drm_encoder *drm_enc, struct
> > drm_crtc *crtc)
> > > -{
> > > -     struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
> > > -     unsigned long lock_flags;
> > > -
> > > -     spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> > > -     /* crtc should always be cleared before re-assigning */
> > > -     WARN_ON(crtc && dpu_enc->crtc);
> > > -     dpu_enc->crtc = crtc;
> > > -     spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > > -}
> > > -
> > >   void dpu_encoder_toggle_vblank_for_crtc(struct drm_encoder
> > *drm_enc,
> > >                                       struct drm_crtc *crtc, bool enable)
> > >   {
> > > @@ -1302,7 +1290,7 @@ void dpu_encoder_toggle_vblank_for_crtc(struct
> > drm_encoder *drm_enc,
> > >       trace_dpu_enc_vblank_cb(DRMID(drm_enc), enable);
> > >
> > >       spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> > > -     if (dpu_enc->crtc != crtc) {
> > > +     if (drm_enc->crtc != crtc) {
> > >               spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > >               return;
> > >       }
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > index 781d41c..edba815 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > @@ -39,14 +39,6 @@ struct msm_display_info {
> > >   };
> > >
> > >   /**
> > > - * dpu_encoder_assign_crtc - Link the encoder to the crtc it's assigned to
> > > - * @encoder: encoder pointer
> > > - * @crtc:    crtc pointer
> > > - */
> > > -void dpu_encoder_assign_crtc(struct drm_encoder *encoder,
> > > -                          struct drm_crtc *crtc);
> > > -
> > > -/**
> > >    * dpu_encoder_toggle_vblank_for_crtc - Toggles vblank interrupts on or
> > off if
> > >    *  the encoder is assigned to the given crtc
> > >    * @encoder:        encoder pointer
> >
> >
> > --
> > With best wishes
> > Dmitry


-- 
With best wishes
Dmitry