Re: [PATCH v9 01/15] drm/msm/disp/dpu: clear dpu_assign_crtc and get crtc from connector state instead of dpu_enc

[Dmitry Baryshkov]

On 21/12/2022 16:10, Vinod Polimera wrote:
> > -----Original Message-----
> > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Sent: Wednesday, December 14, 2022 9:05 PM
> > To: Vinod Polimera (QUIC) <quic_vpolimer@xxxxxxxxxxx>; dri-
> > devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx;
> > freedreno@xxxxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx; robdclark@xxxxxxxxx;
> > dianders@xxxxxxxxxxxx; swboyd@xxxxxxxxxxxx; Kalyan Thota (QUIC)
> > <quic_kalyant@xxxxxxxxxxx>; Kuogee Hsieh (QUIC)
> > <quic_khsieh@xxxxxxxxxxx>; Vishnuvardhan Prodduturi (QUIC)
> > <quic_vproddut@xxxxxxxxxxx>; Bjorn Andersson (QUIC)
> > <quic_bjorande@xxxxxxxxxxx>; Aravind Venkateswaran (QUIC)
> > <quic_aravindh@xxxxxxxxxxx>; Abhinav Kumar (QUIC)
> > <quic_abhinavk@xxxxxxxxxxx>; Sankeerth Billakanti (QUIC)
> > <quic_sbillaka@xxxxxxxxxxx>
> > Subject: Re: [PATCH v9 01/15] drm/msm/disp/dpu: clear dpu_assign_crtc and
> > get crtc from connector state 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 14/12/2022 12:05, Vinod Polimera wrote:
> > > Update crtc retrieval from dpu_enc to dpu_enc connector state,
> > > since new links get set as part of the dpu enc virt mode set.
> > > The dpu_enc->crtc cache is no more needed, hence cleaning it as
> > > part of this change.
> > >
> > > This patch is dependent on the series:
> > > https://patchwork.freedesktop.org/series/110969/
> > >
> > > Signed-off-by: Vinod Polimera <quic_vpolimer@xxxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    |  4 ---
> > >    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 42 +++++++++---------
> > -----------
> > >    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  8 ------
> > >    3 files changed, 13 insertions(+), 41 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > index 3f72d38..289d51e 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > @@ -1029,7 +1029,6 @@ 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 */
> > > @@ -1099,9 +1098,6 @@ 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 a585036..b9b254d 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > @@ -132,11 +132,6 @@ enum dpu_enc_rc_states {
> > >     * @intfs_swapped:  Whether or not the phys_enc interfaces have been
> > swapped
> > >     *                  for partial update right-only cases, such as pingpong
> > >     *                  split where virtual pingpong does not generate IRQs
> > > - * @crtc:            Pointer to the currently assigned crtc. Normally you
> > > - *                   would use crtc->state->encoder_mask to determine the
> > > - *                   link between encoder/crtc. However in this case we need
> > > - *                   to track crtc in the disable() hook which is called
> > > - *                   _after_ encoder_mask is cleared.
> > >     * @connector:              If a mode is set, cached pointer to the active
> > connector
> > >     * @crtc_kickoff_cb:                Callback into CRTC that will flush & start
> > >     *                          all CTL paths
> > > @@ -181,7 +176,6 @@ struct dpu_encoder_virt {
> > >
> > >        bool intfs_swapped;
> > >
> > > -     struct drm_crtc *crtc;
> > >        struct drm_connector *connector;
> > >
> > >        struct dentry *debugfs_root;
> > > @@ -1317,7 +1311,7 @@ static void dpu_encoder_vblank_callback(struct
> > drm_encoder *drm_enc,
> > >                struct dpu_encoder_phys *phy_enc)
> > >    {
> > >        struct dpu_encoder_virt *dpu_enc = NULL;
> > > -     unsigned long lock_flags;
> > > +     struct drm_crtc *crtc;
> > >
> > >        if (!drm_enc || !phy_enc)
> > >                return;
> > > @@ -1325,12 +1319,13 @@ static void dpu_encoder_vblank_callback(struct
> > drm_encoder *drm_enc,
> > >        DPU_ATRACE_BEGIN("encoder_vblank_callback");
> > >        dpu_enc = to_dpu_encoder_virt(drm_enc);
> > >
> > > -     atomic_inc(&phy_enc->vsync_cnt);
> > > +     if (!dpu_enc->connector || !dpu_enc->connector->state ||
> > > +         !dpu_enc->connector->state->crtc)
> > > +             return;
> > >
> > > -     spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> > > -     if (dpu_enc->crtc)
> > > -             dpu_crtc_vblank_callback(dpu_enc->crtc);
> > > -     spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > > +     atomic_inc(&phy_enc->vsync_cnt);
> > > +     crtc = dpu_enc->connector->state->crtc;
> > > +     dpu_crtc_vblank_callback(crtc);
> > >
> > >        DPU_ATRACE_END("encoder_vblank_callback");
> > >    }
> > > @@ -1353,33 +1348,22 @@ 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)
> > >    {
> > >        struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
> > > -     unsigned long lock_flags;
> > > +     struct drm_crtc *new_crtc;
> > >        int i;
> > >
> > >        trace_dpu_enc_vblank_cb(DRMID(drm_enc), enable);
> > >
> > > -     spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> > > -     if (dpu_enc->crtc != crtc) {
> > > -             spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > > +     if (!dpu_enc->connector || !dpu_enc->connector->state)
> > > +             return;
> > > +
> > > +     new_crtc = dpu_enc->connector->state->crtc;
> > > +     if (!new_crtc || new_crtc != crtc) {
> >
> > I don't like going through all the pointers and states without locks.
> > The connector->state can potentially check. So, I'd propose even simpler
> > solution: just store the crtc in the dpu_enc at the creation time. Then
> > you can use the rest of the current dpu_enc->crtc as expected.
>
> Can i do as below.
> After encoder to crtc is pinned, i can update dpu_encoder structure that is attached with drm_enc with the crtc created during drm_obj_init
>
> @@ -816,6 +816,7 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
>                  }
>                  priv->crtcs[priv->num_crtcs++] = crtc;
>                  encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
>                + dpu_encoder_assign_crtc(encoder, crtc);
>                  i++;
>          }

Yes.

> > >                return;
> > >        }
> > > -     spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> > >
> > >        for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> > >                struct dpu_encoder_phys *phys = dpu_enc->phys_encs[i];
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > index 7f3d823..eb9fc7c 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > > @@ -40,14 +40,6 @@ 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