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Message-ID: <CAA8EJppDB-LTiUF1_-2gX8DjGC99Xze9OFFJZEn0VwaJBAAMpQ@mail.gmail.com>
Date: Wed, 8 Jan 2025 20:55:15 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>,
Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>,
Chandan Uddaraju <chandanu@...eaurora.org>, Jeykumar Sankaran <jsanka@...eaurora.org>,
Jordan Crouse <jordan@...micpenguin.net>, Sravanthi Kollukuduru <skolluku@...eaurora.org>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Archit Taneja <architt@...eaurora.org>, Rajesh Yadav <ryadav@...eaurora.org>,
linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org
Cc: Simona Vetter <simona.vetter@...ll.ch>
Subject: Re: [PATCH 6/6] drm/msm/dpu: don't set crtc_state->mode_changed from atomic_check()
On Wed, 8 Jan 2025 at 19:55, Simona Vetter <simona.vetter@...ll.ch> wrote:
>
> On Sun, Dec 22, 2024 at 07:00:46AM +0200, Dmitry Baryshkov wrote:
> > The MSM driver uses drm_atomic_helper_check() which mandates that none
> > of the atomic_check() callbacks toggles crtc_state->mode_changed.
> > Perform corresponding check before calling the drm_atomic_helper_check()
> > function.
> >
> > Fixes: 8b45a26f2ba9 ("drm/msm/dpu: reserve cdm blocks for writeback in case of YUV output")
> > Reported-by: Simona Vetter <simona.vetter@...ll.ch>
> > Closes: https://lore.kernel.org/dri-devel/ZtW_S0j5AEr4g0QW@phenom.ffwll.local/
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> > drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 32 +++++++++++++++++++++++++----
> > drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 4 ++++
> > drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 26 +++++++++++++++++++++++
> > drivers/gpu/drm/msm/msm_atomic.c | 13 +++++++++++-
> > drivers/gpu/drm/msm/msm_kms.h | 7 +++++++
> > 5 files changed, 77 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index 209e6fb605b2d8724935b62001032e7d39540366..b7c3aa8d0e2ca58091deacdeaccb0819d2bf045c 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -753,6 +753,34 @@ static void dpu_encoder_assign_crtc_resources(struct dpu_kms *dpu_kms,
> > cstate->num_mixers = num_lm;
> > }
> >
> > +/**
> > + * dpu_encoder_virt_check_mode_changed: check if full modeset is required
> > + * @drm_enc: Pointer to drm encoder structure
> > + * @crtc_state: Corresponding CRTC state to be checked
> > + * @conn_state: Corresponding Connector's state to be checked
> > + *
> > + * Check if the changes in the object properties demand full mode set.
> > + */
> > +int dpu_encoder_virt_check_mode_changed(struct drm_encoder *drm_enc,
> > + struct drm_crtc_state *crtc_state,
> > + struct drm_connector_state *conn_state)
> > +{
> > + struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
> > + struct msm_display_topology topology;
> > +
> > + DPU_DEBUG_ENC(dpu_enc, "\n");
> > +
> > + /* Using mode instead of adjusted_mode as it wasn't computed yet */
> > + topology = dpu_encoder_get_topology(dpu_enc, &crtc_state->mode, crtc_state, conn_state);
> > +
> > + if (topology.needs_cdm && !dpu_enc->cur_master->hw_cdm)
> > + crtc_state->mode_changed = true;
> > + else if (!topology.needs_cdm && dpu_enc->cur_master->hw_cdm)
> > + crtc_state->mode_changed = true;
> > +
> > + return 0;
> > +}
> > +
> > static int dpu_encoder_virt_atomic_check(
> > struct drm_encoder *drm_enc,
> > struct drm_crtc_state *crtc_state,
> > @@ -786,10 +814,6 @@ static int dpu_encoder_virt_atomic_check(
> >
> > topology = dpu_encoder_get_topology(dpu_enc, adj_mode, crtc_state, conn_state);
> >
> > - if (topology.needs_cdm && !dpu_enc->cur_master->hw_cdm)
> > - crtc_state->mode_changed = true;
> > - else if (!topology.needs_cdm && dpu_enc->cur_master->hw_cdm)
> > - crtc_state->mode_changed = true;
> > /*
> > * Release and Allocate resources on every modeset
> > */
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > index 92b5ee390788d16e85e195a664417896a2bf1cae..da133ee4701a329f566f6f9a7255f2f6d050f891 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > @@ -88,4 +88,8 @@ void dpu_encoder_cleanup_wb_job(struct drm_encoder *drm_enc,
> >
> > bool dpu_encoder_is_valid_for_commit(struct drm_encoder *drm_enc);
> >
> > +int dpu_encoder_virt_check_mode_changed(struct drm_encoder *drm_enc,
> > + struct drm_crtc_state *crtc_state,
> > + struct drm_connector_state *conn_state);
> > +
> > #endif /* __DPU_ENCODER_H__ */
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index dae8a94d3366abfb8937d5f44d8968f1d0691c2d..e2d822f7d785dc0debcb28595029a3e2050b0cf4 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -446,6 +446,31 @@ static void dpu_kms_disable_commit(struct msm_kms *kms)
> > pm_runtime_put_sync(&dpu_kms->pdev->dev);
> > }
> >
> > +static int dpu_kms_check_mode_changed(struct msm_kms *kms, struct drm_atomic_state *state)
> > +{
> > + struct drm_crtc_state *new_crtc_state;
> > + struct drm_connector *connector;
> > + struct drm_connector_state *new_conn_state;
> > + int i;
> > +
> > + for_each_new_connector_in_state(state, connector, new_conn_state, i) {
> > + struct drm_encoder *encoder;
> > +
> > + WARN_ON(!!new_conn_state->best_encoder != !!new_conn_state->crtc);
> > +
> > + if (!new_conn_state->crtc || !new_conn_state->best_encoder)
> > + continue;
> > +
> > + new_crtc_state = drm_atomic_get_new_crtc_state(state, new_conn_state->crtc);
> > +
> > + encoder = new_conn_state->best_encoder;
> > +
> > + dpu_encoder_virt_check_mode_changed(encoder, new_crtc_state, new_conn_state);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static void dpu_kms_flush_commit(struct msm_kms *kms, unsigned crtc_mask)
> > {
> > struct dpu_kms *dpu_kms = to_dpu_kms(kms);
> > @@ -1049,6 +1074,7 @@ static const struct msm_kms_funcs kms_funcs = {
> > .irq = dpu_core_irq,
> > .enable_commit = dpu_kms_enable_commit,
> > .disable_commit = dpu_kms_disable_commit,
> > + .check_mode_changed = dpu_kms_check_mode_changed,
> > .flush_commit = dpu_kms_flush_commit,
> > .wait_flush = dpu_kms_wait_flush,
> > .complete_commit = dpu_kms_complete_commit,
> > diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
> > index a7a2384044ffdb13579cc9a10f56f8de9beca761..364df245e3a209094782ca1b47b752a729b32a5b 100644
> > --- a/drivers/gpu/drm/msm/msm_atomic.c
> > +++ b/drivers/gpu/drm/msm/msm_atomic.c
> > @@ -183,10 +183,16 @@ static unsigned get_crtc_mask(struct drm_atomic_state *state)
> >
> > int msm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> > {
> > + struct msm_drm_private *priv = dev->dev_private;
> > + struct msm_kms *kms = priv->kms;
> > struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> > struct drm_crtc *crtc;
> > - int i;
> > + int i, ret = 0;
> >
> > + /*
> > + * FIXME: stop setting allow_modeset and move this check to the DPU
> > + * driver.
> > + */
>
> I guess there's more work to stop setting allow_modeset? Or was the issue
> there that it breaks userspace that expects ctm changes to be doable
> without modesets?
Yes. And I currently have no way to check that userspace, so for me
it's easier to add a TODO rather than to risk breaking it.
And with your patch going in I think we should add a check that the
allow_modeset flag hasn't been tampered with.
>
> Either way msm patches lgtm, but don't feel confident enough for acks
> except on the first one that reworks the active_change logic to use
> crtc->enable instead for resource allocation.
> -Sima
>
> > for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state,
> > new_crtc_state, i) {
> > if ((old_crtc_state->ctm && !new_crtc_state->ctm) ||
> > @@ -196,6 +202,11 @@ int msm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> > }
> > }
> >
> > + if (kms && kms->funcs && kms->funcs->check_mode_changed)
> > + ret = kms->funcs->check_mode_changed(kms, state);
> > + if (ret)
> > + return ret;
> > +
> > return drm_atomic_helper_check(dev, state);
> > }
> >
> > diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
> > index e60162744c669773b6e5aef824a173647626ab4e..ec2a75af89b09754faef1a07adc9338f7d78161e 100644
> > --- a/drivers/gpu/drm/msm/msm_kms.h
> > +++ b/drivers/gpu/drm/msm/msm_kms.h
> > @@ -59,6 +59,13 @@ struct msm_kms_funcs {
> > void (*enable_commit)(struct msm_kms *kms);
> > void (*disable_commit)(struct msm_kms *kms);
> >
> > + /**
> > + * @check_mode_changed:
> > + *
> > + * Verify if the commit requires a full modeset on one of CRTCs.
> > + */
> > + int (*check_mode_changed)(struct msm_kms *kms, struct drm_atomic_state *state);
> > +
> > /**
> > * Prepare for atomic commit. This is called after any previous
> > * (async or otherwise) commit has completed.
> >
> > --
> > 2.39.5
> >
>
> --
> Simona Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
--
With best wishes
Dmitry
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