[AMD Official Use Only]
-----Original Message----- From: Koenig, Christian Christian.Koenig@amd.com Sent: Tuesday, December 14, 2021 4:00 PM To: Huang, Ray Ray.Huang@amd.com; dri-devel@lists.freedesktop.org; Daniel Vetter daniel.vetter@ffwll.ch; Sumit Semwal sumit.semwal@linaro.org Cc: amd-gfx@lists.freedesktop.org; linux-media@vger.kernel.org; Deucher, Alexander Alexander.Deucher@amd.com; Liu, Monk Monk.Liu@amd.com Subject: Re: [PATCH 1/3] dma-buf: make the flags can be configured during dma fence init
Am 13.12.21 um 07:34 schrieb Huang Rui:
In some user scenarios, the get_timeline_name callback uses the flags to decide which way to return the timeline string name. Once the trace_dma_fence_init event is enabled, it will call get_timeline_name callback to dump the fence structure. However, at this moment, the flags are always 0, and it might trigger some issues in get_timeline_name callback implementation of different gpu driver. So make a member to initialize the flags in dma_fence_init().
Well that doesn't make much sense to me.
None of the dma_fence callbacks is called from the dma_fence_init function (or at least shouldn't). So drivers always have the opportunity to to adjust the flags.
So please explain the rational again?
Once we enable trace_dma_fence_init event, we will call get_driver_name and get_timeline_name callback function to dump the names in dma_fence_init(). At that time, the flags are always 0. However, in amdgpu_fence_get_timeline_name(), it will check the flags (AMDGPU_FENCE_FLAG_EMBED_IN_JOB_BIT) to select which way to get the ring. If the fence should be actually embedded in the job (will be set after that), it still will trigger a kernel panic (please see patch2) because it go with a wrong way. Because we cannot set the flags at the start of dma_fence_init. That is the problem.
Thanks, Ray
Christian.
Signed-off-by: Huang Rui ray.huang@amd.com
drivers/dma-buf/dma-fence.c | 2 +- include/linux/dma-fence.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 066400ed8841..3e0622bf385f 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -952,7 +952,7 @@ dma_fence_init(struct dma_fence *fence, const
struct dma_fence_ops *ops,
fence->lock = lock; fence->context = context; fence->seqno = seqno;
- fence->flags = 0UL;
fence->flags = ops->init_flags; fence->error = 0;
trace_dma_fence_init(fence);
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 1ea691753bd3..f9270c5bc07a 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -131,6 +131,13 @@ struct dma_fence_ops { */ bool use_64bit_seqno;
- /**
* @init_flags:** The initial value of fence flags (A mask of DMA_FENCE_FLAG_*defined).
*/- unsigned long init_flags;
- /**
- @get_driver_name: