Quoting Huang Rui (2018-08-07 11:56:24)
On Tue, Aug 07, 2018 at 11:45:00AM +0100, Chris Wilson wrote:
amdgpu only uses shared-fences internally, but dmabuf importers rely on implicit write hazard tracking via the reservation_object.fence_excl. For example, the importer use the write hazard for timing a page flip to only occur after the exporter has finished flushing its write into the surface. As such, on exporting a dmabuf, we must either flush all outstanding fences (for we do not know which are writes and should have been exclusive) or alternatively create a new exclusive fence that is the composite of all the existing shared fences, and so will only be signaled when all earlier fences are signaled (ensuring that we can not be signaled before the completion of any earlier write).
Testcase: igt/amd_prime/amd-to-i915 Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Alex Deucher alexander.deucher@amd.com Cc: "Christian König" christian.koenig@amd.com
drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 70 ++++++++++++++++++++--- 1 file changed, 62 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c index 1c5d97f4b4dd..47e6ec5510b6 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c @@ -37,6 +37,7 @@ #include "amdgpu_display.h" #include <drm/amdgpu_drm.h> #include <linux/dma-buf.h> +#include <linux/dma-fence-array.h>
static const struct dma_buf_ops amdgpu_dmabuf_ops;
@@ -188,6 +189,57 @@ amdgpu_gem_prime_import_sg_table(struct drm_device *dev, return ERR_PTR(ret); }
+static int +__reservation_object_make_exclusive(struct reservation_object *obj) +{
Why not you move the helper to reservation.c, and then export symbol for this file?
I have not seen anything else that would wish to use this helper. The first task is to solve this issue here before worrying about generalisation. -Chris