On Wed, 25 Jan 2023 at 04:14, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
>
>
> On 6/17/2022 4:33 PM, Dmitry Baryshkov wrote:
> > The array of CRTC in the struct msm_drm_private duplicates a list of
> > CRTCs in the drm_device. Drop it and use the existing list for CRTC
> > enumeration.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > ---
> > drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 2 +-
> > drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 +-
> > drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 2 +-
> > drivers/gpu/drm/msm/msm_drv.c | 44 +++++++++++++-----------
> > drivers/gpu/drm/msm/msm_drv.h | 3 +-
> > 5 files changed, 27 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index e23e2552e802..e79f0a8817ac 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -806,7 +806,7 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
> > ret = PTR_ERR(crtc);
> > return ret;
> > }
> > - priv->crtcs[priv->num_crtcs++] = crtc;
> > + priv->num_crtcs++;
> > }
> >
> > /* All CRTCs are compatible with all encoders */
> > diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> > index fb48c8c19ec3..7449c1693e45 100644
> > --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> > @@ -337,7 +337,7 @@ static int modeset_init(struct mdp4_kms *mdp4_kms)
> > goto fail;
> > }
> >
> > - priv->crtcs[priv->num_crtcs++] = crtc;
> > + priv->num_crtcs++;
> > }
> >
> > /*
> > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > index 3d5621a68f85..36808990f840 100644
> > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > @@ -497,7 +497,7 @@ static int modeset_init(struct mdp5_kms *mdp5_kms)
> > DRM_DEV_ERROR(dev->dev, "failed to construct crtc %d (%d)\n", i, ret);
> > goto fail;
> > }
> > - priv->crtcs[priv->num_crtcs++] = crtc;
> > + priv->num_crtcs++;
> > }
> >
> > /*
> > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > index 1aab6bf86278..567e77dae43b 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.c
> > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > @@ -149,7 +149,7 @@ static void msm_irq_uninstall(struct drm_device *dev)
> >
> > struct msm_vblank_work {
> > struct work_struct work;
> > - int crtc_id;
> > + struct drm_crtc *crtc;
> > bool enable;
> > struct msm_drm_private *priv;
> > };
> > @@ -162,15 +162,15 @@ static void vblank_ctrl_worker(struct work_struct *work)
> > struct msm_kms *kms = priv->kms;
> >
>
> Is there any chance of vbl_work->crtc becoming NULL before this gets
> executed?
No. The worker is created in vblank_ctrl_queue_work. The
vbl_work->crtc is filled at the time of creation.
> So do we need to protect this like
>
> if (vbl_work->enable && vbl_work->crtc)
>
> Because the layers below this dont seem to have NULL protection.
>
>
> > if (vbl_work->enable)
> > - kms->funcs->enable_vblank(kms, priv->crtcs[vbl_work->crtc_id]);
> > + kms->funcs->enable_vblank(kms, vbl_work->crtc);
> > else
> > - kms->funcs->disable_vblank(kms, priv->crtcs[vbl_work->crtc_id]);
> > + kms->funcs->disable_vblank(kms, vbl_work->crtc);
> >
> > kfree(vbl_work);
> > }
> >
> > static int vblank_ctrl_queue_work(struct msm_drm_private *priv,
> > - int crtc_id, bool enable)
> > + struct drm_crtc *crtc, bool enable)
> > {
> > struct msm_vblank_work *vbl_work;
> >
> > @@ -180,7 +180,7 @@ static int vblank_ctrl_queue_work(struct msm_drm_private *priv,
> >
> > INIT_WORK(&vbl_work->work, vblank_ctrl_worker);
> >
> > - vbl_work->crtc_id = crtc_id;
> > + vbl_work->crtc = crtc;
> > vbl_work->enable = enable;
> > vbl_work->priv = priv;
> >
> > @@ -354,7 +354,8 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
> > struct msm_drm_private *priv = dev_get_drvdata(dev);
> > struct drm_device *ddev;
> > struct msm_kms *kms;
> > - int ret, i;
> > + struct drm_crtc *crtc;
> > + int ret;
> >
> > if (drm_firmware_drivers_only())
> > return -ENODEV;
> > @@ -427,20 +428,23 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
> > ddev->mode_config.funcs = &mode_config_funcs;
> > ddev->mode_config.helper_private = &mode_config_helper_funcs;
> >
> > - for (i = 0; i < priv->num_crtcs; i++) {
> > + drm_for_each_crtc(crtc, ddev) {
> > + struct msm_drm_thread *ev_thread;
> > +
> > /* initialize event thread */
> > - priv->event_thread[i].crtc_id = priv->crtcs[i]->base.id;
> > - priv->event_thread[i].dev = ddev;
> > - priv->event_thread[i].worker = kthread_create_worker(0,
> > - "crtc_event:%d", priv->event_thread[i].crtc_id);
> > - if (IS_ERR(priv->event_thread[i].worker)) {
> > - ret = PTR_ERR(priv->event_thread[i].worker);
> > + ev_thread = &priv->event_thread[drm_crtc_index(crtc)];
> > + ev_thread->crtc = crtc;
> > + ev_thread->dev = ddev;
> > + ev_thread->worker = kthread_create_worker(0,
> > + "crtc_event:%d", ev_thread->crtc->base.id);
>
> Please correct me if wrong.
>
> Today, other than just populating the name for the worker is the
> ev_thread->crtc used anywhere?
>
> If so, can we just drop crtc from msm_drm_thread and while creating the
> worker just use kthread_create_worker(0, "crtc_event:%d", crtc->base.id);
It seems so. I'll take a look for v2.
However your questions actually raised another question in my head. I
went on looking for the reason for such complex vblank handling. It
was added by Hai Li in the commit 78b1d470d57d ("drm/msm: Enable
clocks during enable/disable_vblank() callbacks"). However I don't
fully understand why the code will toggle vblank handling while the
DPU/MDP5/MDP4 device is not resumed already. Maybe I just missed
something here. Do you know the story behind the change?
>
> > + if (IS_ERR(ev_thread->worker)) {
> > + ret = PTR_ERR(ev_thread->worker);
> > DRM_DEV_ERROR(dev, "failed to create crtc_event kthread\n");
> > - priv->event_thread[i].worker = NULL;
> > + ev_thread->worker = NULL;
> > goto err_msm_uninit;
> > }
> >
> > - sched_set_fifo(priv->event_thread[i].worker->task);
> > + sched_set_fifo(ev_thread->worker->task);
> > }
> >
> > ret = drm_vblank_init(ddev, priv->num_crtcs);
> > @@ -563,25 +567,23 @@ static void msm_postclose(struct drm_device *dev, struct drm_file *file)
> > int msm_crtc_enable_vblank(struct drm_crtc *crtc)
> > {
> > struct drm_device *dev = crtc->dev;
> > - unsigned int pipe = crtc->index;
> > struct msm_drm_private *priv = dev->dev_private;
> > struct msm_kms *kms = priv->kms;
> > if (!kms)
> > return -ENXIO;
> > - drm_dbg_vbl(dev, "crtc=%u", pipe);
> > - return vblank_ctrl_queue_work(priv, pipe, true);
> > + drm_dbg_vbl(dev, "crtc=%u", crtc->base.id);
> > + return vblank_ctrl_queue_work(priv, crtc, true);
> > }
> >
> > void msm_crtc_disable_vblank(struct drm_crtc *crtc)
> > {
> > struct drm_device *dev = crtc->dev;
> > - unsigned int pipe = crtc->index;
> > struct msm_drm_private *priv = dev->dev_private;
> > struct msm_kms *kms = priv->kms;
> > if (!kms)
> > return;
> > - drm_dbg_vbl(dev, "crtc=%u", pipe);
> > - vblank_ctrl_queue_work(priv, pipe, false);
> > + drm_dbg_vbl(dev, "crtc=%u", crtc->base.id);
> > + vblank_ctrl_queue_work(priv, crtc, false);
> > }
> >
> > /*
> > diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> > index 08388d742d65..0e98b6f161df 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.h
> > +++ b/drivers/gpu/drm/msm/msm_drv.h
> > @@ -102,7 +102,7 @@ struct msm_display_topology {
> > /* Commit/Event thread specific structure */
> > struct msm_drm_thread {
> > struct drm_device *dev;
> > - unsigned int crtc_id;
> > + struct drm_crtc *crtc;
> > struct kthread_worker *worker;
> > };
> >
> > @@ -178,7 +178,6 @@ struct msm_drm_private {
> > struct workqueue_struct *wq;
> >
> > unsigned int num_crtcs;
> > - struct drm_crtc *crtcs[MAX_CRTCS];
> >
> > struct msm_drm_thread event_thread[MAX_CRTCS];
> >
--
With best wishes
Dmitry
