Messages in this thread | | | Date | Mon, 13 Jul 2020 17:57:52 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 1/3] habanalabs: implement dma-fence mechanism |
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On Mon, Jul 13, 2020 at 06:54:22PM +0300, Oded Gabbay wrote: > From: Ofir Bitton <obitton@habana.ai> > > Instead of using standard dma-fence mechanism designed for GPU's, we > introduce our own implementation based on the former one. This > implementation is much more sparse than the original, contains only > mandatory functionality required by the driver.
Sad you can't use the in-kernel code for this, I really don't understand what's wrong with using it as-is.
Daniel, why do we need/want duplicate code floating around in the tree like this?
Copying code leads to errors, here's some documentation ones:
> --- /dev/null > +++ b/drivers/misc/habanalabs/hl_dma_fence.c > @@ -0,0 +1,338 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Fence mechanism for dma-buf and to allow for asynchronous dma access
Is that what this still does?
> + * > + * Copyright (C) 2012 Canonical Ltd > + * Copyright (C) 2012 Texas Instruments > + * > + * Authors: > + * Rob Clark <robdclark@gmail.com> > + * Maarten Lankhorst <maarten.lankhorst@canonical.com> > + * > + * The dma_fence module is a copy of dma-fence at drivers/dma-buf.
"The hl_dma_fence" module...
And is it a stand-alone module? Or just a single file?
> + * This was done due to an explicit request by GPU developers who asked not > + * to use the dma-buf module because we aren't part of DRM subsystem.
Why is dma-buf only for use for DRM?
If it is, should the symbol namespace be set to that to catch users that want to use it for their own code?
> + * This copy was stripped from all extra features that habanalabs driver > + * doesn't use, including the uapi interface dma-buf exposes. > + * In addition, we removed the callbacks because the only usage is from inside > + * habanalabs driver > + */ > + > +#include "hl_dma_fence.h" > +#include "habanalabs.h" > +#include <linux/slab.h> > +#include <linux/export.h> > +#include <linux/atomic.h> > +#include <linux/sched/signal.h> > + > +/** > + * DOC: DMA fences overview > + * > + * DMA fences, represented by &struct hl_dma_fence, are the kernel internal > + * synchronization primitive for DMA operations like GPU rendering, video > + * encoding/decoding, or displaying buffers on a screen.
I don't think this is correct anymore, right? :(
> --- /dev/null > +++ b/drivers/misc/habanalabs/hl_dma_fence.h > @@ -0,0 +1,148 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Fence mechanism for dma-buf to allow for asynchronous dma access > + * > + * Copyright (C) 2012 Canonical Ltd > + * Copyright (C) 2012 Texas Instruments > + * > + * Authors: > + * Rob Clark <robdclark@gmail.com> > + * Maarten Lankhorst <maarten.lankhorst@canonical.com> > + * > + * The dma_fence module is a copy of dma-fence at drivers/dma-buf.
Same comments here for the .h file.
thanks,
greg k-h
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