On Sun, Apr 29, 2018 at 09:11:31AM +0200, Christian König wrote:
Am 27.04.2018 um 08:17 schrieb Daniel Vetter:
When this was introduced in
commit a519435a96597d8cd96123246fea4ae5a6c90b02 Author: Christian König christian.koenig@amd.com Date: Tue Oct 20 16:34:16 2015 +0200
dma-buf/fence: add fence_wait_any_timeout function v2there was a restriction added that this only works if the dma-fence uses the dma_fence_default_wait hook. Which works for amdgpu, which is the only caller. Well, until you share some buffers with e.g. i915, then you get an -EINVAL.
But there's really no reason for this, because all drivers must support callbacks. The special ->wait hook is only as an optimization; if the driver needs to create a worker thread for an active callback, then it can avoid to do that if it knows that there's a process context available already. So ->wait is just an optimization, just using the logic in dma_fence_default_wait() should work for all drivers.
Let's remove this restriction.
Mhm, that was intentional introduced because for radeon that is not only an optimization, but mandatory for correct operation.
On the other hand radeon isn't using this function, so it should be fine as long as the Intel driver can live with it.
Well dma-buf already requires that dma_fence_add_callback works correctly. And so do various users of it as soon as you engage in a bit of buffer sharing. I guess whomever cares about buffer sharing with radeon gets to fix this (you need to spawn a kthread or whatever in ->enable_signaling which does the same work as your optimized ->wait callback).
But yeah, I'm definitely not making things work with this series, just a bit more obvious that there's a problem already. -Daniel
Christian.
Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Gustavo Padovan gustavo@padovan.org Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Cc: Christian König christian.koenig@amd.com Cc: Alex Deucher alexander.deucher@amd.com
drivers/dma-buf/dma-fence.c | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 7b5b40d6b70e..59049375bd19 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -503,11 +503,6 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count, for (i = 0; i < count; ++i) { struct dma_fence *fence = fences[i];
if (fence->ops->wait != dma_fence_default_wait) {ret = -EINVAL;goto fence_rm_cb;}- cb[i].task = current; if (dma_fence_add_callback(fence, &cb[i].base, dma_fence_default_wait_cb)) {