On 12/11/2015 05:11 AM, john.c.harri...@intel.com wrote:
> From: John Harrison
>
> The fence object used inside the request structure requires a sequence
> number. Although this is not used by the i915 driver itself, it could
> potentially be used by non-i915 code if the fence is passed outside of
> the driver. This is the intention as it allows external kernel drivers
> and user applications to wait on batch buffer completion
> asynchronously via the dma-buff fence API.
>
> To ensure that such external users are not confused by strange things
> happening with the seqno, this patch adds in a per context timeline
> that can provide a guaranteed in-order seqno value for the fence. This
> is safe because the scheduler will not re-order batch buffers within a
> context - they are considered to be mutually dependent.
>
> v2: New patch in series.
>
> v3: Renamed/retyped timeline structure fields after review comments by
> Tvrtko Ursulin.
>
> Added context information to the timeline's name string for better
> identification in debugfs output.
>
> For: VIZ-5190
> Signed-off-by: John Harrison
> Cc: Tvrtko Ursulin
> ---
> drivers/gpu/drm/i915/i915_drv.h | 25 ---
> drivers/gpu/drm/i915/i915_gem.c | 80
> +
> drivers/gpu/drm/i915/i915_gem_context.c | 15 ++-
> drivers/gpu/drm/i915/intel_lrc.c| 8
> drivers/gpu/drm/i915/intel_ringbuffer.h | 1 -
> 5 files changed, 111 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index caf7897..7d6a7c0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -841,6 +841,15 @@ struct i915_ctx_hang_stats {
> bool banned;
> };
>
> +struct i915_fence_timeline {
> + charname[32];
> + unsignedfence_context;
> + unsignednext;
> +
> + struct intel_context *ctx;
> + struct intel_engine_cs *ring;
> +};
> +
> /* This must match up with the value previously used for execbuf2.rsvd1. */
> #define DEFAULT_CONTEXT_HANDLE 0
>
> @@ -885,6 +894,7 @@ struct intel_context {
> struct drm_i915_gem_object *state;
> struct intel_ringbuffer *ringbuf;
> int pin_count;
> + struct i915_fence_timeline fence_timeline;
> } engine[I915_NUM_RINGS];
>
> struct list_head link;
> @@ -2177,13 +2187,10 @@ void i915_gem_track_fb(struct drm_i915_gem_object
> *old,
> struct drm_i915_gem_request {
> /**
>* Underlying object for implementing the signal/wait stuff.
> - * NB: Never call fence_later() or return this fence object to user
> - * land! Due to lazy allocation, scheduler re-ordering, pre-emption,
> - * etc., there is no guarantee at all about the validity or
> - * sequentiality of the fence's seqno! It is also unsafe to let
> - * anything outside of the i915 driver get hold of the fence object
> - * as the clean up when decrementing the reference count requires
> - * holding the driver mutex lock.
> + * NB: Never return this fence object to user land! It is unsafe to
> + * let anything outside of the i915 driver get hold of the fence
> + * object as the clean up when decrementing the reference count
> + * requires holding the driver mutex lock.
>*/
> struct fence fence;
>
> @@ -2263,6 +2270,10 @@ int i915_gem_request_alloc(struct intel_engine_cs
> *ring,
> struct drm_i915_gem_request **req_out);
> void i915_gem_request_cancel(struct drm_i915_gem_request *req);
>
> +int i915_create_fence_timeline(struct drm_device *dev,
> +struct intel_context *ctx,
> +struct intel_engine_cs *ring);
> +
> static inline bool i915_gem_request_completed(struct drm_i915_gem_request
> *req)
> {
> return fence_is_signaled(&req->fence);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 0801738..7a37fb7 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2665,9 +2665,32 @@ static const char
> *i915_gem_request_get_driver_name(struct fence *req_fence)
>
> static const char *i915_gem_request_get_timeline_name(struct fence
> *req_fence)
> {
> - struct drm_i915_gem_request *req = container_of(req_fence,
> - typeof(*req), fence);
> - return req->ring->name;
> + struct drm_i915_gem_request *req;
> + struct i915_fence_timeline *timeline;
> +
> + req = container_of(req_fence, typeof(*req), fence);
> + timeline = &req->ctx->engine[req->ring->id].fence_timeline;
> +
> + return timeline->name;
> +}
> +
> +static void i915_gem_request_timeline_value_str(struct fence *req_fence,
> char *str, int size)
> +{
> + struct drm_i915_gem_request *req;
> +
> + req = container_of(req_fence, typeof(*req), fence);
> +
> +
