On Fri, Jul 26, 2019 at 06:15:46PM +0200, Daniel Vetter wrote:
> On Fri, Jul 26, 2019 at 4:44 PM Brian Starkey <brian.star...@arm.com> wrote:
> >
> > On Fri, Jul 26, 2019 at 04:23:56PM +0200, Daniel Vetter wrote:
> > > On Fri, Jul 26, 2019 at 08:13:00AM +0000, Lowry Li (Arm Technology China)
> > > wrote:
> > > > Current DRM-CORE accepts the writeback_job with a empty fb, but that
> > > > is an invalid job for HW, so need to skip it when commit it to HW.
> > > >
> > > > Signed-off-by: Lowry Li (Arm Technology China) <lowry...@arm.com>
> > >
> > > Hm, this sounds a bit like an oversight in core writeback code? Not sure
> > > how this can even happen, setting up a writeback job without an fb sounds
> > > a bit like a bug to me at least ...
> > >
> > > If we don't have a good reason for why other hw needs to accept this, then
> > > imo this needs to be rejected in shared code. For consistent behaviour
> > > across all writeback supporting drivers.
> > > -Daniel
> >
> > I think it's only this way to simplify the drm_writeback_set_fb()
> > implementation in the case where the property is set more than once in
> > the same commit (to something valid, and then 0).
> >
> > The core could indeed handle it - drm_writeback_set_fb() would check
> > fb. If it's NULL and there's no writeback job, then it can just early
> > return. If it's NULL and there's already a writeback job then it
> > should drop the reference on the existing fb and free that job.
> >
> > Could lead to the job getting alloc/freed multiple times if userspace
> > is insane, but meh.
>
> Generally these consistency checks need to be in in the atomic_check
> phase, not when we set properties. So either somewhere in the helpers,
> or in drm_atomic_connector_check() if we want it in core, enforced for
> everyone.
> -Daniel
Thanks Daniel and Brian's comments. Agree with it to add the check in
atomic_check phase. Will send an update patch.
-Lowry
> >
> > -Brian
> >
> > >
> > > > ---
> > > > drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 2 +-
> > > > drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c | 9 ++++++++-
> > > > 2 files changed, 9 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > > > b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > > > index 2fed1f6..372e99a 100644
> > > > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > > > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> > > > @@ -265,7 +265,7 @@ void komeda_crtc_handle_event(struct komeda_crtc
> > > > *kcrtc,
> > > > komeda_pipeline_update(slave, old->state);
> > > >
> > > > conn_st = wb_conn ? wb_conn->base.base.state : NULL;
> > > > -if (conn_st && conn_st->writeback_job)
> > > > +if (conn_st && conn_st->writeback_job && conn_st->writeback_job->fb)
> > > > drm_writeback_queue_job(&wb_conn->base, conn_st);
> > > >
> > > > /* step 2: notify the HW to kickoff the update */
> > > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c
> > > > b/drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c
> > > > index 9787745..8e2ef63 100644
> > > > --- a/drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c
> > > > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c
> > > > @@ -52,9 +52,16 @@
> > > > struct komeda_data_flow_cfg dflow;
> > > > int err;
> > > >
> > > > -if (!writeback_job || !writeback_job->fb)
> > > > +if (!writeback_job)
> > > > return 0;
> > > >
> > > > +if (!writeback_job->fb) {
> > > > +if (writeback_job->out_fence)
> > > > +DRM_DEBUG_ATOMIC("Out fence required on a invalid writeback job.\n");
> > > > +
> > > > +return writeback_job->out_fence ? -EINVAL : 0;
> > > > +}
> > > > +
> > > > if (!crtc_st->active) {
> > > > DRM_DEBUG_ATOMIC("Cannot write the composition result out on a
> > > > inactive CRTC.\n");
> > > > return -EINVAL;
> > > > --
> > > > 1.9.1
> > > >
> > > > _______________________________________________
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> > > > dri-devel@lists.freedesktop.org
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> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
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>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
--
Regards,
Lowry
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