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Date: Tue, 8 Nov 2016 17:11:58 +0100
From: Daniel Vetter <daniel@...ll.ch>
To: Brian Starkey <brian.starkey@....com>
Cc: Gustavo Padovan <gustavo@...ovan.org>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Daniel Stone <daniels@...labora.com>,
Daniel Vetter <daniel.vetter@...ll.ch>,
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>,
Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: [PATCH v7 1/3] drm/fence: add in-fences support
On Tue, Nov 08, 2016 at 03:27:14PM +0000, Brian Starkey wrote:
> Hi Gustavo,
>
> On Tue, Nov 08, 2016 at 03:54:48PM +0900, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> >
> > There is now a new property called IN_FENCE_FD attached to every plane
> > state that receives sync_file fds from userspace via the atomic commit
> > IOCTL.
> >
> > The fd is then translated to a fence (that may be a fence_array
> > 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"
> > - re-introduce WARN_ON if fence set but no fb
> >
> > - rebase after fence -> dma_fence rename
> >
> > Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> > ---
> > drivers/gpu/drm/Kconfig | 1 +
> > drivers/gpu/drm/drm_atomic.c | 14 ++++++++++++++
> > drivers/gpu/drm/drm_atomic_helper.c | 3 +++
> > drivers/gpu/drm/drm_crtc.c | 6 ++++++
> > drivers/gpu/drm/drm_plane.c | 1 +
> > include/drm/drm_crtc.h | 5 +++++
> > 6 files changed, 30 insertions(+)
> >
> > 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..d1ae463 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;
> > +
>
> Sorry, I'm a bit late to bring this up but what's the expected
> behaviour of a commit which sets OUT_FENCE twice (first with a valid
> fence, then with -1 later in the list)? Maybe you need to actually
> clear state->fence for -1.
Good point, we should probaly reject that. Since ->fence should autoclear
(I totally missed that one) we should check for an existing fence and fail
if it's set already.
> > + 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) {
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 75ad01d..26a067f 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -3114,6 +3114,9 @@ void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
> > {
> > if (state->fb)
> > drm_framebuffer_unreference(state->fb);
> > +
> > + if (state->fence)
> > + dma_fence_put(state->fence);
> > }
> > EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
> >
>
> It looks like you need to add something in
> __drm_atomic_helper_plane_duplicate_state() to either get a reference
> on the fence or set state->fence = NULL, because the memcpy() there
> will copy the pointer.
Clearing to NULL would be best, since that matches the meaning of the -1
we return to userspace when reading the property. I guess I get to retract
my r-b.
-Daniel
>
> Cheers,
> -Brian
>
> > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> > index 13441e2..7878bfd 100644
> > --- a/drivers/gpu/drm/drm_crtc.c
> > +++ b/drivers/gpu/drm/drm_crtc.c
> > @@ -397,6 +397,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
> > return -ENOMEM;
> > dev->mode_config.prop_fb_id = prop;
> >
> > + prop = drm_property_create_signed_range(dev, DRM_MODE_PROP_ATOMIC,
> > + "IN_FENCE_FD", -1, INT_MAX);
> > + if (!prop)
> > + return -ENOMEM;
> > + dev->mode_config.prop_in_fence_fd = prop;
> > +
> > prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
> > "CRTC_ID", DRM_MODE_OBJECT_CRTC);
> > if (!prop)
> > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> > index 249c0ae..3957ef8 100644
> > --- a/drivers/gpu/drm/drm_plane.c
> > +++ b/drivers/gpu/drm/drm_plane.c
> > @@ -137,6 +137,7 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
> >
> > if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
> > drm_object_attach_property(&plane->base, config->prop_fb_id, 0);
> > + drm_object_attach_property(&plane->base, config->prop_in_fence_fd, -1);
> > drm_object_attach_property(&plane->base, config->prop_crtc_id, 0);
> > drm_object_attach_property(&plane->base, config->prop_crtc_x, 0);
> > drm_object_attach_property(&plane->base, config->prop_crtc_y, 0);
> > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> > index fa1aa21..719b6a8 100644
> > --- a/include/drm/drm_crtc.h
> > +++ b/include/drm/drm_crtc.h
> > @@ -1201,6 +1201,11 @@ struct drm_mode_config {
> > */
> > struct drm_property *prop_fb_id;
> > /**
> > + * @prop_in_fence_fd: Sync File fd representing the incoming fences
> > + * for a Plane.
> > + */
> > + struct drm_property *prop_in_fence_fd;
> > + /**
> > * @prop_crtc_id: Default atomic plane property to specify the
> > * &drm_crtc.
> > */
> > --
> > 2.5.5
> >
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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