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Date: Wed, 12 Oct 2022 12:01:20 +0000
From: Vinod Polimera <vpolimer@....qualcomm.com>
To: "dmitry.baryshkov@...aro.org" <dmitry.baryshkov@...aro.org>,
"Vinod Polimera (QUIC)" <quic_vpolimer@...cinc.com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
"freedreno@...ts.freedesktop.org" <freedreno@...ts.freedesktop.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"robdclark@...il.com" <robdclark@...il.com>,
"dianders@...omium.org" <dianders@...omium.org>,
"swboyd@...omium.org" <swboyd@...omium.org>,
"Kalyan Thota (QUIC)" <quic_kalyant@...cinc.com>,
"Kuogee Hsieh (QUIC)" <quic_khsieh@...cinc.com>,
"Vishnuvardhan Prodduturi (QUIC)" <quic_vproddut@...cinc.com>,
"Bjorn Andersson (QUIC)" <quic_bjorande@...cinc.com>,
"Aravind Venkateswaran (QUIC)" <quic_aravindh@...cinc.com>,
"Abhinav Kumar (QUIC)" <quic_abhinavk@...cinc.com>,
"Sankeerth Billakanti (QUIC)" <quic_sbillaka@...cinc.com>
Subject: RE: [PATCH v7 01/15] drm/msm/disp/dpu: clear dpu_assign_crtc and get
crtc from connector state instead of dpu_enc
> -----Original Message-----
> From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Sent: Tuesday, September 13, 2022 10:36 PM
> To: Vinod Polimera (QUIC) <quic_vpolimer@...cinc.com>; dri-
> devel@...ts.freedesktop.org; linux-arm-msm@...r.kernel.org;
> freedreno@...ts.freedesktop.org; devicetree@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org; robdclark@...il.com;
> dianders@...omium.org; swboyd@...omium.org; Kalyan Thota (QUIC)
> <quic_kalyant@...cinc.com>; Kuogee Hsieh (QUIC)
> <quic_khsieh@...cinc.com>; Vishnuvardhan Prodduturi (QUIC)
> <quic_vproddut@...cinc.com>; Bjorn Andersson (QUIC)
> <quic_bjorande@...cinc.com>; Aravind Venkateswaran (QUIC)
> <quic_aravindh@...cinc.com>; Abhinav Kumar (QUIC)
> <quic_abhinavk@...cinc.com>; Sankeerth Billakanti (QUIC)
> <quic_sbillaka@...cinc.com>
> Subject: Re: [PATCH v7 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 13/09/2022 20:04, Dmitry Baryshkov wrote:
> > On 13/09/2022 17:51, 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.
> >>
> >> Signed-off-by: Vinod Polimera <quic_vpolimer@...cinc.com>
> >> ---
> >> drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 4 ----
> >> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 35
> >> ++++++++++++-----------------
> >> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 8 -------
> >> 3 files changed, 14 insertions(+), 33 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> >> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> >> index 13ce321..8ec9a13 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 9c6817b..0c7d8b5 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;
> >> @@ -1288,6 +1282,7 @@ static void dpu_encoder_vblank_callback(struct
> >> drm_encoder *drm_enc,
> >> struct dpu_encoder_phys *phy_enc)
> >> {
> >> struct dpu_encoder_virt *dpu_enc = NULL;
> >> + struct drm_crtc *crtc;
> >> unsigned long lock_flags;
> >> if (!drm_enc || !phy_enc)
> >> @@ -1298,9 +1293,14 @@ static void
> dpu_encoder_vblank_callback(struct
> >> drm_encoder *drm_enc,
> >> atomic_inc(&phy_enc->vsync_cnt);
> >> + if (!dpu_enc->connector || !dpu_enc->connector->state)
> >> + return;
> >> +
> >> + crtc = dpu_enc->connector->state->crtc;
> >> +
> >> spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> >> - if (dpu_enc->crtc)
> >> - dpu_crtc_vblank_callback(dpu_enc->crtc);
> >> + if (crtc)
> >> + dpu_crtc_vblank_callback(crtc);
> >> spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> >
> > Stephen's comment about reading the state from outside of the lock and
> > then using local variable under spinlock is still valid. Moreover I'm
> > not sure that enc_spinlock protects connector's state. I'd say one has
> > to take the modesetting lock here.
>
> s/Stephen's/Doug's/
As this is in interrupt context , we cannot use modeset lock here and connector does not have the spinlock to protect state.
since state swap happens after commit to hw done, which is after vblank processing, i was thinking it should be okay to drop the spinlock while accessing connector state.
I have updated the patch with the changes in v8, please do review.
>
> --
> With best wishes
> Dmitry
Thanks
Vinod P.
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