Re: [PATCH 9/9] drm/i915: Mark imported dma-buf objects as being coherent

Mika Kuoppala
2016-07-15T11:33:58Z

Chris Wilson <chris@chris-wilson.co.uk> writes:

> A foreign dma-buf does not share our cache domain tracking, and we rely
> on the producer ensuring cache coherency. Marking them as being in the
> CPU domain is incorrect.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_gem_dmabuf.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> index 80bbe43a2e92..c7d734248ed0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -299,6 +299,8 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
> drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
> i915_gem_object_init(obj, &i915_gem_object_dmabuf_ops);
> obj->base.import_attach = attach;
> + obj->base.read_domains = I915_GEM_DOMAIN_GTT;

I was a confused about the coherency guarantees of this _GTT.

But after chatting with Chris I am convinced that what comes to
coherency for other guests and sharing, this is it.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

-Mika

> + obj->base.write_domain = 0;
>
> return &obj->base;
>
> --
> 2.8.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx