Add helper to check if fence is array.
v2: Comments from Chris Wilson
- remove ternary if from ops comparison
- add EXPORT_SYMBOL(fence_array_ops)
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
We've got a complaint saying that the description was quite obtuse and
indeed it was. This patch tries to improve it.
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
There is only a single user of dma_buf_debugfs_create_file() and that
one got the function pointer cast wrong. With that one fixed, there is
no need to have a wrapper for debugfs_create_file(), just call it
directly.
With no users left, we can remove dma_buf_debugfs_create_file().
While at it, simplify the error handling in dma_buf_init_debugfs()
slightly.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1466339491-12639-2-git-send-email-minipli@googlemail.com
Change the error handling in dma_buf_init_debugfs() to remove the
"dma_buf" directory if creating the "bufinfo" file fails. No need to
have an empty debugfs directory around.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
The callback function dma_buf_describe() returns an int not void so the
function pointer cast in dma_buf_show() is wrong. dma_buf_describe() can
also fail when acquiring the mutex gets interrupted so always returning
0 in dma_buf_show() is wrong, too.
Fix both issues by avoiding the indirection via dma_buf_show() and call
dma_buf_describe() directly. Rename it to dma_buf_debug_show() to get it
in line with the other functions.
This type mismatch was caught by the PaX RAP plugin.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: PaX Team <pageexec@freemail.hu>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
As promised, piles of prep work all around:
- drm_atomic_state rework, prep for nonblocking commit helpers
- fence patches from Gustavo and Christian to prep for atomic fences and
some cool work in ttm/amdgpu from Christian
- drm event prep for both nonblocking commit and atomic fences
- Gustavo seems on a crusade against the non-kms-native version of the
vblank functions.
- prep work from Boris to nuke all the silly ->best_encoder
implementations we have (we really only need that for truly dynamic
cases like dvi-i vs dvi-d or dp mst selecting the right transcoder on
intel)
- prep work from Laurent to rework the format handling functions
- and few small things all over
* tag 'topic/drm-misc-2016-06-07' of git://anongit.freedesktop.org/drm-intel: (47 commits)
drm/dsi: Implement set tear scanline
drm/fb_cma_helper: Implement fb_mmap callback
drm/qxl: Remove useless drm_fb_get_bpp_depth() call
drm/ast: Remove useless drm_fb_get_bpp_depth() call
drm/atomic: Fix remaining places where !funcs->best_encoder is valid
drm/core: Change declaration for gamma_set.
Documentation: add fence-array to kernel DocBook
drm/shmobile: use drm_crtc_vblank_{get,put}()
drm/radeon: use drm_crtc_vblank_{get,put}()
drm/qxl: use drm_crtc_vblank_{get,put}()
drm/atmel: use drm_crtc_vblank_{get,put}()
drm/armada: use drm_crtc_vblank_{get,put}()
drm/amdgpu: use drm_crtc_vblank_{get,put}()
drm/virtio: use drm_crtc_send_vblank_event()
drm/udl: use drm_crtc_send_vblank_event()
drm/qxl: use drm_crtc_send_vblank_event()
drm/atmel: use drm_crtc_send_vblank_event()
drm/armada: use drm_crtc_send_vblank_event()
drm/doc: Switch to sphinx/rst fixed-width quoting
drm/doc: Drop kerneldoc for static functions in drm_irq.c
...
If @signal_on_any is true the fence array signals if any fence in the array
signals, otherwise it signals when all fences in the array signal.
v2: fix signaled test and add comment suggested by Chris Wilson.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464786612-5010-4-git-send-email-deathsimple@vodafone.de
struct fence_array inherits from struct fence and carries a
collection of fences that needs to be waited together.
It is useful to translate a sync_file to a fence to remove the complexity
of dealing with sync_files on DRM drivers. So even if there are many
fences in the sync_file that needs to waited for a commit to happen,
they all get added to the fence_collection and passed for DRM use as
a standard struct fence.
That means that no changes needed to any driver besides supporting fences.
To avoid fence_array's fence allocates a new timeline if needed (when
combining fences from different timelines).
v2: Comments by Daniel Vetter:
- merge fence_collection_init() and fence_collection_add()
- only add callbacks at ->enable_signalling()
- remove fence_collection_put()
- check for type on to_fence_collection()
- adjust fence_is_later() and fence_later() to WARN_ON() if they
are used with collection fences.
v3: - Initialize fence_cb.node at fence init.
Comments by Chris Wilson:
- return "unbound" on fence_collection_get_timeline_name()
- don't stop adding callbacks if one fails
- remove redundant !! on fence_collection_enable_signaling()
- remove redundant () on fence_collection_signaled
- use fence_default_wait() instead
v4 (chk): Rework, simplification and cleanup:
- Drop FENCE_NO_CONTEXT handling, always allocate a context.
- Rename to fence_array.
- Return fixed driver name.
- Register only one callback at a time.
- Document that create function takes ownership of array.
v5 (chk): More work and fixes:
- Avoid deadlocks by adding all callbacks at once again.
- Stop trying to remove the callbacks.
- Provide context and sequence number for the array fence.
v6 (chk): Fixes found during testing
- Fix stupid typo in _enable_signaling().
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
[danvet: Improve commit message as suggested by Gustavo.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464786612-5010-3-git-send-email-deathsimple@vodafone.de
Fence contexts are created on the fly (for example) by the GPU scheduler used
in the amdgpu driver as a result of an userspace request. Because of this
userspace could in theory force a wrap around of the 32bit context number
if it doesn't behave well.
Avoid this by increasing the context number to 64bits. This way even when
userspace manages to allocate a billion contexts per second it takes more
than 500 years for the context number to wrap around.
v2: fix printf formats as well.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1464786612-5010-2-git-send-email-deathsimple@vodafone.de
Replace explicit computation of vma page count by a call to
vma_pages().
Also, include <linux/mm.h>
Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
sync_file is useful to connect one or more fences to the file. The file is
used by userspace to track fences between drivers that share DMA bufs.
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Just a bit of wording polish plus mentioning that it can fail and must
be restarted.
Requested by Sumit.
v2: Fix them typos (Hans).
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tiago Vignatti <tiago.vignatti@intel.com>
Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
CC: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: intel-gfx@lists.freedesktop.org
Cc: devel@driverdev.osuosl.org
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Drivers, especially i915.ko, can fail during the initial migration of a
dma-buf for CPU access. However, the error code from the driver was not
being propagated back to ioctl and so userspace was blissfully ignorant
of the failure. Rendering corruption ensues.
Whilst fixing the ioctl to return the error code from
dma_buf_start_cpu_access(), also do the same for
dma_buf_end_cpu_access(). For most drivers, dma_buf_end_cpu_access()
cannot fail. i915.ko however, as most drivers would, wants to avoid being
uninterruptible (as would be required to guarrantee no failure when
flushing the buffer to the device). As userspace already has to handle
errors from the SYNC_IOCTL, take advantage of this to be able to restart
the syscall across signals.
This fixes a coherency issue for i915.ko as well as reducing the
uninterruptible hold upon its BKL, the struct_mutex.
Fixes commit c11e391da2
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu Feb 11 20:04:51 2016 -0200
dma-buf: Add ioctls to allow userspace to flush
Testcase: igt/gem_concurrent_blit/*dmabuf*interruptible
Testcase: igt/prime_mmap_coherency/ioctl-errors
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tiago Vignatti <tiago.vignatti@intel.com>
Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
CC: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: intel-gfx@lists.freedesktop.org
Cc: devel@driverdev.osuosl.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1458331359-2634-1-git-send-email-chris@chris-wilson.co.uk
The userspace might need some sort of cache coherency management e.g. when CPU
and GPU domains are being accessed through dma-buf at the same time. To
circumvent this problem there are begin/end coherency markers, that forward
directly to existing dma-buf device drivers vfunc hooks. Userspace can make use
of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The sequence would be
used like following:
- mmap dma-buf fd
- for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
want (with the new data being consumed by the GPU or say scanout device)
- munmap once you don't need the buffer any more
v2 (Tiago): Fix header file type names (u64 -> __u64)
v3 (Tiago): Add documentation. Use enum dma_buf_sync_flags to the begin/end
dma-buf functions. Check for overflows in start/length.
v4 (Tiago): use 2d regions for sync.
v5 (Tiago): forget about 2d regions (v4); use _IOW in DMA_BUF_IOCTL_SYNC and
remove range information from struct dma_buf_sync.
v6 (Tiago): use __u64 structured padded flags instead enum. Adjust
documentation about the recommendation on using sync ioctls.
v7 (Tiago): Alex' nit on flags definition and being even more wording in the
doc about sync usage.
v9 (Tiago): remove useless is_dma_buf_file check. Fix sync.flags conditionals
and its mask order check. Add <linux/types.h> include in dma-buf.h.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1455228291-29640-1-git-send-email-tiago.vignatti@intel.com
This patch removes range-based information used for optimizations in
begin_cpu_access and end_cpu_access.
We don't have any user nor implementation using range-based flush. It seems a
consensus that if we ever want something like that again (or even more robust
using 2D, 3D sub-range regions) we can use the upcoming dma-buf sync ioctl for
such.
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1450820214-12509-3-git-send-email-tiago.vignatti@intel.com
Waiting for the first fence in an array of fences to signal.
This is useful for device driver specific resource managers
and also Vulkan needs something similar.
v2: more parameter checks, handling for timeout==0,
remove NULL entry support, better callback removal.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
- WARNING: Missing a blank line after declarations
- WARNING: line over 80 characters
- WARNING: please, no space before tabs
Signed-off-by: Jagan Teki <jteki@openedev.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Add reference counting on a kernel module that exports dma-buf and
implements its operations. This prevents the module from being unloaded
while DMABUF file is in use.
The original patch [1] was submitted by Tomasz Stanislawski, but this
is a simpler way to do it.
v3: call module_put() as late as possible, per gregkh's comment.
v2: move owner to struct dma_buf, and use DEFINE_DMA_BUF_EXPORT_INFO
macro to simplify the change.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[1]: https://lkml.org/lkml/2012/8/8/163
At present, dma_buf_export() takes a series of parameters, which
makes it difficult to add any new parameters for exporters, if required.
Make it simpler by moving all these parameters into a struct, and pass
the struct * as parameter to dma_buf_export().
While at it, unite dma_buf_export_named() with dma_buf_export(), and
change all callers accordingly.
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
It was causing the return value of fence_is_signaled to be ignored, making
reservation objects signal too early.
Cc: stable@vger.kernel.org
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
When specified timeout is zero for fence_wait_timeout, just check if the fence
is signaled or not without wait.
Signed-off-by: Jammy Zhou <Jammy.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-By: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
When the timeout value passed to reservation_object_wait_timeout_rcu
is zero, no wait should be done if the fences are not signaled.
Return '1' for idle and '0' for busy if the specified timeout is '0'
to keep consistent with the case of non-zero timeout.
v2: call fence_put if not signaled in the case of timeout==0
v3: switch to reservation_object_test_signaled_rcu
Signed-off-by: Jammy Zhou <Jammy.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-By: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
This patch fix speeling typo found in html files within
Documentation/DocBook/device-drivers.
It is because html files are generated from comments in source,
so I have to fix comments in the source.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
kerneldoc doesn't know how to parse variables, so don't let it try.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
This adds some extra functions to deal with rcu.
reservation_object_get_fences_rcu() will obtain the list of shared
and exclusive fences without obtaining the ww_mutex.
reservation_object_wait_timeout_rcu() will wait on all fences of the
reservation_object, without obtaining the ww_mutex.
reservation_object_test_signaled_rcu() will test if all fences of the
reservation_object are signaled without using the ww_mutex.
reservation_object_get_excl and reservation_object_get_list require
the reservation object to be held, updating requires
write_seqcount_begin/end. If only the exclusive fence is needed,
rcu_dereference followed by fence_get_rcu can be used, if the shared
fences are needed it's recommended to use the supplied functions.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-By: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the list of shared fences to a struct, and return it in
reservation_object_get_list().
Add reservation_object_get_excl to get the exclusive fence.
Add reservation_object_reserve_shared(), which reserves space
in the reservation_object for 1 more shared fence.
reservation_object_add_shared_fence() and
reservation_object_add_excl_fence() are used to assign a new
fence to a reservation_object pointer, to complete a reservation.
Changes since v1:
- Add reservation_object_get_excl, reorder code a bit.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This allows reservation objects to be used in dma-buf. it's required
for implementing polling support on the fences that belong to a dma-buf.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Mauro Carvalho Chehab <m.chehab@samsung.com> #drivers/media/v4l2-core/
Acked-by: Thomas Hellstrom <thellstrom@vmware.com> #drivers/gpu/drm/ttm
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net> #drivers/gpu/drm/armada/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This type of fence can be used with hardware synchronization for simple
hardware that can block execution until the condition
(dma_buf[offset] - value) >= 0 has been met when WAIT_GEQUAL is used,
or (dma_buf[offset] != 0) has been met when WAIT_NONZERO is set.
A software fallback still has to be provided in case the fence is used
with a device that doesn't support this mechanism. It is useful to expose
this for graphics cards that have an op to support this.
Some cards like i915 can export those, but don't have an option to wait,
so they need the software fallback.
I extended the original patch by Rob Clark.
v1: Original
v2: Renamed from bikeshed to seqno, moved into dma-fence.c since
not much was left of the file. Lots of documentation added.
v3: Use fence_ops instead of custom callbacks. Moved to own file
to avoid circular dependency between dma-buf.h and fence.h
v4: Add spinlock pointer to seqno_fence_init
v5: Add condition member to allow wait for != 0.
Fix small style errors pointed out by checkpatch.
v6: Move to a separate file. Fix up api changes in fences.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Rob Clark <robdclark@gmail.com> #v4
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A fence can be attached to a buffer which is being filled or consumed
by hw, to allow userspace to pass the buffer without waiting to another
device. For example, userspace can call page_flip ioctl to display the
next frame of graphics after kicking the GPU but while the GPU is still
rendering. The display device sharing the buffer with the GPU would
attach a callback to get notified when the GPU's rendering-complete IRQ
fires, to update the scan-out address of the display, without having to
wake up userspace.
A driver must allocate a fence context for each execution ring that can
run in parallel. The function for this takes an argument with how many
contexts to allocate:
+ fence_context_alloc()
A fence is transient, one-shot deal. It is allocated and attached
to one or more dma-buf's. When the one that attached it is done, with
the pending operation, it can signal the fence:
+ fence_signal()
To have a rough approximation whether a fence is fired, call:
+ fence_is_signaled()
The dma-buf-mgr handles tracking, and waiting on, the fences associated
with a dma-buf.
The one pending on the fence can add an async callback:
+ fence_add_callback()
The callback can optionally be cancelled with:
+ fence_remove_callback()
To wait synchronously, optionally with a timeout:
+ fence_wait()
+ fence_wait_timeout()
When emitting a fence, call:
+ trace_fence_emit()
To annotate that a fence is blocking on another fence, call:
+ trace_fence_annotate_wait_on(fence, on_fence)
A default software-only implementation is provided, which can be used
by drivers attaching a fence to a buffer when they have no other means
for hw sync. But a memory backed fence is also envisioned, because it
is common that GPU's can write to, or poll on some memory location for
synchronization. For example:
fence = custom_get_fence(...);
if ((seqno_fence = to_seqno_fence(fence)) != NULL) {
dma_buf *fence_buf = seqno_fence->sync_buf;
get_dma_buf(fence_buf);
... tell the hw the memory location to wait ...
custom_wait_on(fence_buf, seqno_fence->seqno_ofs, fence->seqno);
} else {
/* fall-back to sw sync * /
fence_add_callback(fence, my_cb);
}
On SoC platforms, if some other hw mechanism is provided for synchronizing
between IP blocks, it could be supported as an alternate implementation
with it's own fence ops in a similar way.
enable_signaling callback is used to provide sw signaling in case a cpu
waiter is requested or no compatible hardware signaling could be used.
The intention is to provide a userspace interface (presumably via eventfd)
later, to be used in conjunction with dma-buf's mmap support for sw access
to buffers (or for userspace apps that would prefer to do their own
synchronization).
v1: Original
v2: After discussion w/ danvet and mlankhorst on #dri-devel, we decided
that dma-fence didn't need to care about the sw->hw signaling path
(it can be handled same as sw->sw case), and therefore the fence->ops
can be simplified and more handled in the core. So remove the signal,
add_callback, cancel_callback, and wait ops, and replace with a simple
enable_signaling() op which can be used to inform a fence supporting
hw->hw signaling that one or more devices which do not support hw
signaling are waiting (and therefore it should enable an irq or do
whatever is necessary in order that the CPU is notified when the
fence is passed).
v3: Fix locking fail in attach_fence() and get_fence()
v4: Remove tie-in w/ dma-buf.. after discussion w/ danvet and mlankorst
we decided that we need to be able to attach one fence to N dma-buf's,
so using the list_head in dma-fence struct would be problematic.
v5: [ Maarten Lankhorst ] Updated for dma-bikeshed-fence and dma-buf-manager.
v6: [ Maarten Lankhorst ] I removed dma_fence_cancel_callback and some comments
about checking if fence fired or not. This is broken by design.
waitqueue_active during destruction is now fatal, since the signaller
should be holding a reference in enable_signalling until it signalled
the fence. Pass the original dma_fence_cb along, and call __remove_wait
in the dma_fence_callback handler, so that no cleanup needs to be
performed.
v7: [ Maarten Lankhorst ] Set cb->func and only enable sw signaling if
fence wasn't signaled yet, for example for hardware fences that may
choose to signal blindly.
v8: [ Maarten Lankhorst ] Tons of tiny fixes, moved __dma_fence_init to
header and fixed include mess. dma-fence.h now includes dma-buf.h
All members are now initialized, so kmalloc can be used for
allocating a dma-fence. More documentation added.
v9: Change compiler bitfields to flags, change return type of
enable_signaling to bool. Rework dma_fence_wait. Added
dma_fence_is_signaled and dma_fence_wait_timeout.
s/dma// and change exports to non GPL. Added fence_is_signaled and
fence_enable_sw_signaling calls, add ability to override default
wait operation.
v10: remove event_queue, use a custom list, export try_to_wake_up from
scheduler. Remove fence lock and use a global spinlock instead,
this should hopefully remove all the locking headaches I was having
on trying to implement this. enable_signaling is called with this
lock held.
v11:
Use atomic ops for flags, lifting the need for some spin_lock_irqsaves.
However I kept the guarantee that after fence_signal returns, it is
guaranteed that enable_signaling has either been called to completion,
or will not be called any more.
Add contexts and seqno to base fence implementation. This allows you
to wait for less fences, by testing for seqno + signaled, and then only
wait on the later fence.
Add FENCE_TRACE, FENCE_WARN, and FENCE_ERR. This makes debugging easier.
An CONFIG_DEBUG_FENCE will be added to turn off the FENCE_TRACE
spam, and another runtime option can turn it off at runtime.
v12:
Add CONFIG_FENCE_TRACE. Add missing documentation for the fence->context
and fence->seqno members.
v13:
Fixup CONFIG_FENCE_TRACE kconfig description.
Move fence_context_alloc to fence.
Simplify fence_later.
Kill priv member to fence_cb.
v14:
Remove priv argument from fence_add_callback, oops!
v15:
Remove priv from documentation.
Explicitly include linux/atomic.h.
v16:
Add trace events.
Import changes required by android syncpoints.
v17:
Use wake_up_state instead of try_to_wake_up. (Colin Cross)
Fix up commit description for seqno_fence. (Rob Clark)
v18:
Rename release_fence to fence_release.
Move to drivers/dma-buf/.
Rename __fence_is_signaled and __fence_signal to *_locked.
Rename __fence_init to fence_init.
Make fence_default_wait return a signed long, and fix wait ops too.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com> #use smp_mb__before_atomic()
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
