Re: [Intel-gfx] [PATCH v3 1/6] drm/i915: Add functions to set/get moving fence

[Matthew Auld <matthew.auld@intel.com>]

On 14/11/2021 11:12, Thomas Hellström wrote:
> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> 
> We want to get rid of i915_vma tracking to simplify the code and
> lifetimes. Add a way to set/put the moving fence, in preparation for
> removing the tracking.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_object.c | 37 ++++++++++++++++++++++
>   drivers/gpu/drm/i915/gem/i915_gem_object.h |  9 ++++++
>   2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> index 591ee3cb7275..ec4313836597 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> @@ -33,6 +33,7 @@
>   #include "i915_gem_object.h"
>   #include "i915_memcpy.h"
>   #include "i915_trace.h"
> +#include "i915_gem_ttm.h"
>   
>   static struct kmem_cache *slab_objects;
>   
> @@ -726,6 +727,42 @@ static const struct drm_gem_object_funcs i915_gem_object_funcs = {
>   	.export = i915_gem_prime_export,
>   };
>   
> +struct dma_fence *
> +i915_gem_object_get_moving_fence(struct drm_i915_gem_object *obj)
> +{
> +	return dma_fence_get(i915_gem_to_ttm(obj)->moving);
> +}
> +
> +void i915_gem_object_set_moving_fence(struct drm_i915_gem_object *obj,
> +				      struct dma_fence *fence)
> +{
> +	dma_fence_put(i915_gem_to_ttm(obj)->moving);
> +
> +	i915_gem_to_ttm(obj)->moving = dma_fence_get(fence);
> +}

Are these also assert_object_held()? Should we maybe squash this patch 
with the first user?

> +
> +int i915_gem_object_wait_moving_fence(struct drm_i915_gem_object *obj,
> +				      bool intr)
> +{
> +	struct dma_fence *fence = i915_gem_to_ttm(obj)->moving;
> +	int ret;
> +
> +	assert_object_held(obj);
> +	if (!fence)
> +		return 0;
> +
> +	ret = dma_fence_wait(fence, intr);
> +	if (ret)
> +		return ret;
> +
> +	if (fence->error)
> +		return fence->error;
> +
> +	i915_gem_to_ttm(obj)->moving = NULL;
> +	dma_fence_put(fence);
> +	return 0;
> +}
> +
>   #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>   #include "selftests/huge_gem_object.c"
>   #include "selftests/huge_pages.c"
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> index 133963b46135..36bf3e2e602f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> @@ -517,6 +517,15 @@ i915_gem_object_finish_access(struct drm_i915_gem_object *obj)
>   	i915_gem_object_unpin_pages(obj);
>   }
>   
> +struct dma_fence *
> +i915_gem_object_get_moving_fence(struct drm_i915_gem_object *obj);
> +
> +void i915_gem_object_set_moving_fence(struct drm_i915_gem_object *obj,
> +				      struct dma_fence *fence);
> +
> +int i915_gem_object_wait_moving_fence(struct drm_i915_gem_object *obj,
> +				      bool intr);
> +
>   void i915_gem_object_set_cache_coherency(struct drm_i915_gem_object *obj,
>   					 unsigned int cache_level);
>   bool i915_gem_object_can_bypass_llc(struct drm_i915_gem_object *obj);
>