The dma-buf holds an array of fences, which unlike the sync_file are not
sealed and may be modified at runtime. For the purpose of computing
dependencies, we can take a snapshot of the fences within the
dma-buf's reservation object (converting them into a fence-array) and
uses that as our input fence to this execbuf. It also provides a means
for us to pass in an array of fences and ask to only wait on the first
being signaled.
In short, it allows dma-buf to be used as a *reusable* container for
multiple signaling objects, and for scheduling execbuf between clients.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Jason Ekstrand <jason.ekstr...@intel.com>
Cc: Gustavo Padovan <gust...@padovan.org>
---
drivers/gpu/drm/i915/i915_drv.c | 1 +
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 62 ++++++++++++++++++++++++++++--
include/uapi/drm/i915_drm.h | 26 +++++++++++--
3 files changed, 83 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 43da9cf65233..de8f40b0bd58 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -352,6 +352,7 @@ static int i915_getparam(struct drm_device *dev, void *data,
case I915_PARAM_HAS_EXEC_SOFTPIN:
case I915_PARAM_HAS_EXEC_ASYNC:
case I915_PARAM_HAS_EXEC_FENCE:
+ case I915_PARAM_HAS_EXEC_FENCE_DMABUF:
/* For the time being all of these are always true;
* if some supported hardware does not have one of these
* features this value needs to be provided from
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index da0846fe2ad6..eb9b9e333b9b 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -26,6 +26,7 @@
*
*/
+#include <linux/dma-buf.h>
#include <linux/dma_remapping.h>
#include <linux/reservation.h>
#include <linux/sync_file.h>
@@ -1576,6 +1577,49 @@ eb_select_engine(struct drm_i915_private *dev_priv,
return engine;
}
+static struct dma_fence *
+dma_buf_get_fence(int fd, unsigned int flags)
+{
+ struct dma_buf *dmabuf;
+ struct dma_fence_array *array;
+ struct dma_fence **shared, *excl;
+ unsigned int count, i;
+
+ dmabuf = dma_buf_get(fd);
+ if (IS_ERR(dmabuf))
+ return ERR_CAST(dmabuf);
+
+ shared = NULL;
+ count = 0;
+ if (flags & I915_EXEC_FENCE_EXCL) {
+ excl = reservation_object_get_excl_rcu(dmabuf->resv);
+ } else {
+ int err;
+
+ err = reservation_object_get_fences_rcu(dmabuf->resv,
+ &excl, &count, &shared);
+ if (err) {
+ array = ERR_PTR(err);
+ goto out_put;
+ }
+ }
+
+ if (excl)
+ array = dma_fence_array_create(1, &excl, 0, 0, false);
+ else if (shared)
+ array = dma_fence_array_create(count, shared, 0, 0,
+ flags & I915_EXEC_FENCE_ANY);
+ else
+ array = NULL;
+
+ for (i = 0 ; i < count; i++)
+ dma_fence_put(shared[i]);
+ kfree(shared);
+out_put:
+ dma_buf_put(dmabuf);
+ return &array->base;
+}
+
static int
i915_gem_do_execbuffer(struct drm_device *dev, void *data,
struct drm_file *file,
@@ -1640,9 +1684,21 @@ i915_gem_do_execbuffer(struct drm_device *dev, void
*data,
}
if (args->flags & I915_EXEC_FENCE_IN) {
- in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
- if (!in_fence)
- return -EINVAL;
+ int fd = lower_32_bits(args->rsvd2);
+
+ in_fence = dma_buf_get_fence(fd, args->flags);
+ if (IS_ERR(in_fence)) {
+ if (in_fence != ERR_PTR(-EINVAL))
+ return PTR_ERR(in_fence);
+
+ if (args->flags &
+ (I915_EXEC_FENCE_ANY | I915_EXEC_FENCE_EXCL))
+ return -EINVAL;
+
+ in_fence = sync_file_get_fence(fd);
+ if (!in_fence)
+ return -EINVAL;
+ }
}
if (args->flags & I915_EXEC_FENCE_OUT) {
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 3554495bef13..ebc7641b5252 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -412,6 +412,12 @@ typedef struct drm_i915_irq_wait {
*/
#define I915_PARAM_HAS_EXEC_FENCE 44
+/* Query whether DRM_I915_GEM_EXECBUFFER2 supports using a dma-buf fd as the
+ * in-fence for explicit fence support. See I915_EXEC_FENCE_IN and
+ * I915_EXEC_FENCE_ANY.
+ */
+#define I915_PARAM_HAS_EXEC_FENCE_DMABUF 45
+
typedef struct drm_i915_getparam {
__s32 param;
/*
@@ -865,8 +871,8 @@ struct drm_i915_gem_execbuffer2 {
#define I915_EXEC_RESOURCE_STREAMER (1<<15)
/* Setting I915_EXEC_FENCE_IN implies that lower_32_bits(rsvd2) represent
- * a sync_file fd to wait upon (in a nonblocking manner) prior to executing
- * the batch.
+ * a sync_file or dma-buf fd to wait upon (in a nonblocking manner) prior
+ * to executing the batch.
*
* Returns -EINVAL if the sync_file fd cannot be found.
*/
@@ -889,7 +895,21 @@ struct drm_i915_gem_execbuffer2 {
*/
#define I915_EXEC_FENCE_OUT (1<<17)
-#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_OUT<<1))
+/* If the I915_EXEC_FENCE_IN refers to a dma-buf fd, a fence is created from
+ * its reservation object and it may contain just the exclusive fence, or
+ * an array of all shared fences. Setting I915_EXEC_FENCE_EXCL implies that
+ * the execbuf should only wait for the current exclusive fence to be signaled
+ * before execution.
+ */
+#define I915_EXEC_FENCE_EXCL (1<<18)
+
+/* If the I915_EXEC_FENCE_IN refers to a dma-buf fd, a fence is created from
+ * its reservation object and it may either be signaled on the first fence
+ * within to complet or it may wait for all fences within to be complete.
+ */
+#define I915_EXEC_FENCE_ANY (1<<19)
+
+#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_ANY<<1))
#define I915_EXEC_CONTEXT_ID_MASK (0xffffffff)
#define i915_execbuffer2_set_context_id(eb2, context) \
--
2.11.0
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