Re: [PATCH 22/53] drm/i915: Update i915_switch_context() to take a request structure

Tomas Elf
2015-03-05T18:08:12Z

On 19/02/2015 17:17, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
>
> Now that the request is guaranteed to specify the context, it is possible to
> update the context switch code to use requests rather than ring and context
> pairs. This patch updates i915_switch_context() accordingly.
>
> Also removed the warning that the request's context must match the last context
> switch's context. As the context switch now gets the context object from the
> request structure, there is no longer any scope for the two to become out of
> step.
>
> For: VIZ-5115
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 3 +--
> drivers/gpu/drm/i915/i915_gem.c | 4 +---
> drivers/gpu/drm/i915/i915_gem_context.c | 19 +++++++++----------
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 +-
> 4 files changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 618a841..e9cc343 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2992,8 +2992,7 @@ void i915_gem_context_reset(struct drm_device *dev);
> int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
> int i915_gem_context_enable(struct drm_i915_gem_request *req);
> void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
> -int i915_switch_context(struct intel_engine_cs *ring,
> - struct intel_context *to);
> +int i915_switch_context(struct drm_i915_gem_request *req);
> struct intel_context *
> i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id);
> void i915_gem_context_free(struct kref *ctx_ref);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 64288e3..0c7e1bd 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2470,8 +2470,6 @@ int __i915_add_request(struct intel_engine_cs *ring,
> WARN_ON(request->batch_obj && obj);
> request->batch_obj = obj;
>
> - WARN_ON(request->ctx != ring->last_context);
> -
> request->emitted_jiffies = jiffies;
> list_add_tail(&request->list, &ring->request_list);
> request->file_priv = NULL;
> @@ -3114,7 +3112,7 @@ int i915_gpu_idle(struct drm_device *dev)
> if (ret)
> return ret;
>
> - ret = i915_switch_context(req->ring, ring->default_context);
> + ret = i915_switch_context(req);
> if (ret) {
> i915_gem_request_unreference(req);
> return ret;
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 04d2a20..b326f8d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -414,7 +414,7 @@ int i915_gem_context_enable(struct drm_i915_gem_request *req)
>
> ret = ring->init_context(req->ring, ring->default_context);
> } else
> - ret = i915_switch_context(req->ring, ring->default_context);
> + ret = i915_switch_context(req);
>
> if (ret) {
> DRM_ERROR("ring init context: %d\n", ret);
> @@ -693,8 +693,7 @@ unpin_out:
>
> /**
> * i915_switch_context() - perform a GPU context switch.
> - * @ring: ring for which we'll execute the context switch
> - * @to: the context to switch to
> + * @req: request for which we'll execute the context switch
> *
> * The context life cycle is simple. The context refcount is incremented and
> * decremented by 1 and create and destroy. If the context is in use by the GPU,
> @@ -705,25 +704,25 @@ unpin_out:
> * switched by writing to the ELSP and requests keep a reference to their
> * context.
> */
> -int i915_switch_context(struct intel_engine_cs *ring,
> - struct intel_context *to)
> +int i915_switch_context(struct drm_i915_gem_request *req)
> {
> + struct intel_engine_cs *ring = req->ring;
> struct drm_i915_private *dev_priv = ring->dev->dev_private;
>
> WARN_ON(i915.enable_execlists);
> WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
>
> - if (to->legacy_hw_ctx.rcs_state == NULL) { /* We have the fake context */
> - if (to != ring->last_context) {
> - i915_gem_context_reference(to);
> + if (req->ctx->legacy_hw_ctx.rcs_state == NULL) { /* We have the fake context */
> + if (req->ctx != ring->last_context) {
> + i915_gem_context_reference(req->ctx);
> if (ring->last_context)
> i915_gem_context_unreference(ring->last_context);
> - ring->last_context = to;
> + ring->last_context = req->ctx;
> }
> return 0;
> }
>
> - return do_switch(ring, to);
> + return do_switch(req->ring, req->ctx);
> }
>
> static bool contexts_enabled(struct drm_device *dev)
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 2cd0579..1e2fc80 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1190,7 +1190,7 @@ i915_gem_ringbuffer_submission(struct i915_execbuffer_params *params,
> if (ret)
> goto error;
>
> - ret = i915_switch_context(ring, params->ctx);
> + ret = i915_switch_context(params->request);
> if (ret)
> goto error;
>
>

Reviewed-by: Tomas Elf <tomas.elf@intel.com>

Thanks,
Tomas