On Thu, Aug 5, 2021 at 3:47 AM Daniel Vetter daniel.vetter@ffwll.ch wrote:
There's only one exclusive slot, and we must not break the ordering.
Adding a new exclusive fence drops all previous fences from the dma_resv. To avoid violating the signalling order we err on the side of over-synchronizing by waiting for the existing fences, even if userspace asked us to ignore them.
A better fix would be to us a dma_fence_chain or _array like e.g. amdgpu now uses, but
- msm has a synchronous dma_fence_wait for anything from another context, so doesn't seem to care much,
- and it probably makes sense to lift this into dma-resv.c code as a proper concept, so that drivers don't have to hack up their own solution each on their own.
v2: Improve commit message per Lucas' suggestion.
Cc: Lucas Stach l.stach@pengutronix.de Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Rob Clark robdclark@gmail.com Cc: Sean Paul sean@poorly.run Cc: linux-arm-msm@vger.kernel.org Cc: freedreno@lists.freedesktop.org
a-b
drivers/gpu/drm/msm/msm_gem_submit.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c index fb5a2eab27a2..66633dfd58a2 100644 --- a/drivers/gpu/drm/msm/msm_gem_submit.c +++ b/drivers/gpu/drm/msm/msm_gem_submit.c @@ -330,7 +330,8 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit) return ret; }
if (no_implicit)
/* exclusive fences must be ordered */if (no_implicit && !write) continue; ret = drm_sched_job_add_implicit_dependencies(&submit->base,-- 2.32.0