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Date: Fri, 28 Oct 2016 10:32:42 -0200
From: Gustavo Padovan <gustavo@...ovan.org>
To: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Daniel Stone <daniels@...labora.com>,
Rob Clark <robdclark@...il.com>,
Greg Hackmann <ghackmann@...gle.com>,
John Harrison <John.C.Harrison@...el.com>,
laurent.pinchart@...asonboard.com, seanpaul@...gle.com,
marcheu@...gle.com, m.chehab@...sung.com,
Sumit Semwal <sumit.semwal@...aro.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Brian Starkey <brian.starkey@....com>,
Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: [PATCH v6 4/6] drm/fence: add in-fences support
2016-10-28 Daniel Vetter <daniel@...ll.ch>:
> On Thu, Oct 27, 2016 at 05:37:09PM -0200, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> >
> > There is now a new property called FENCE_FD attached to every plane
> > state that receives the sync_file fd from userspace via the atomic commit
> > IOCTL.
> >
> > The fd is then translated to a fence (that may be a fence_collection
> > subclass or just a normal fence) and then used by DRM to fence_wait() for
> > all fences in the sync_file to signal. So it only commits when all
> > framebuffers are ready to scanout.
> >
> > v2: Comments by Daniel Vetter:
> > - remove set state->fence = NULL in destroy phase
> > - accept fence -1 as valid and just return 0
> > - do not call fence_get() - sync_file_fences_get() already calls it
> > - fence_put() if state->fence is already set, in case userspace
> > set the property more than once.
> >
> > v3: WARN_ON if fence is set but state has no FB
> >
> > v4: Comment from Maarten Lankhorst
> > - allow set fence with no related fb
> >
> > v5: rename FENCE_FD to IN_FENCE_FD
> >
> > v6: Comments by Daniel Vetter:
> > - rename plane_state->in_fence back to "fence"
> >
> > - rebase after fence -> dma_fence rename
> >
> > Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
>
> Looks good, but I'll wait with full review with all the fence patches
> until the igts show up. It's much easier to check for gabs in input
> validation code if you also have the testcases at hand. A few comments
> below.
> -Daniel
>
> > ---
> > drivers/gpu/drm/Kconfig | 1 +
> > drivers/gpu/drm/drm_atomic.c | 15 +++++++++++++++
> > drivers/gpu/drm/drm_atomic_helper.c | 5 +++--
> > drivers/gpu/drm/drm_crtc.c | 6 ++++++
> > drivers/gpu/drm/drm_plane.c | 1 +
> > include/drm/drm_crtc.h | 5 +++++
> > 6 files changed, 31 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > index 483059a..43cb33d 100644
> > --- a/drivers/gpu/drm/Kconfig
> > +++ b/drivers/gpu/drm/Kconfig
> > @@ -12,6 +12,7 @@ menuconfig DRM
> > select I2C
> > select I2C_ALGOBIT
> > select DMA_SHARED_BUFFER
> > + select SYNC_FILE
> > help
> > Kernel-level support for the Direct Rendering Infrastructure (DRI)
> > introduced in XFree86 4.0. If you say Y here, you need to select
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 5e73954..28d9366 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -30,6 +30,7 @@
> > #include <drm/drm_atomic.h>
> > #include <drm/drm_mode.h>
> > #include <drm/drm_plane_helper.h>
> > +#include <linux/sync_file.h>
> >
> > #include "drm_crtc_internal.h"
> >
> > @@ -686,6 +687,17 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
> > drm_atomic_set_fb_for_plane(state, fb);
> > if (fb)
> > drm_framebuffer_unreference(fb);
> > + } else if (property == config->prop_in_fence_fd) {
> > + if (U642I64(val) == -1)
> > + return 0;
> > +
> > + if (state->fence)
> > + dma_fence_put(state->fence);
> > +
> > + state->fence = sync_file_get_fence(val);
> > + if (!state->fence)
> > + return -EINVAL;
> > +
> > } else if (property == config->prop_crtc_id) {
> > struct drm_crtc *crtc = drm_crtc_find(dev, val);
> > return drm_atomic_set_crtc_for_plane(state, crtc);
> > @@ -747,6 +759,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
> >
> > if (property == config->prop_fb_id) {
> > *val = (state->fb) ? state->fb->base.id : 0;
> > + } else if (property == config->prop_in_fence_fd) {
> > + *val = -1;
> > } else if (property == config->prop_crtc_id) {
> > *val = (state->crtc) ? state->crtc->base.id : 0;
> > } else if (property == config->prop_crtc_x) {
> > @@ -1752,6 +1766,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
> > drm_mode_object_unreference(obj);
> > }
> >
> > +
>
> Spurios whitespace.
>
> > if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
> > for_each_crtc_in_state(state, crtc, crtc_state, i) {
> > struct drm_pending_vblank_event *e;
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 75ad01d..c34da9e 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -1034,8 +1034,6 @@ int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
> > if (!plane_state->fence)
> > continue;
> >
> > - WARN_ON(!plane_state->fb);
> > -
>
> Why this? We don't allow a plane to be enabled without an fb, and adding a
> fence to a plane which is disabled sounds likea bug. We probably should
> have a bit of code in the core atomic check code to make sure userspace
> never asks for a fence when the plane is off.
This was Maarten's suggestion that we should be able to sent a fence to
determine when then plane should be disabled. Not sure which usecase he
had in mind.
Gustavo
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