Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> [ text/plain ]
> This is so that we have symmetry with intel_lrc.c and avoid a source of
> if (i915.enable_execlists) layering violation within i915_gem_context.c -
> that is we move the specific handling of the dev_priv->kernel_context
> for legacy submission into the legacy submission code.
>
> This depends upon the init/fini ordering between contexts and engines
> already defined by intel_lrc.c, and also exporting the context alignment
> required for pinning the legacy context.
>
> v2: Separate out pin/unpin context funcs for greater symmetry with
> intel_lrc. One more step towards unifying behaviour between the two
> classes of engines and towards fixing another bug in i915_switch_context
> vs requests.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 2 ++
> drivers/gpu/drm/i915/i915_gem_context.c | 27 ++--------------
> drivers/gpu/drm/i915/intel_ringbuffer.c | 55 +++++++++++++++++++++++++++++++++
> 3 files changed, 60 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index e4c8e341655c..19d0194c728f 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -867,6 +867,8 @@ struct i915_gem_context {
> u32 user_handle;
> #define CONTEXT_NO_ZEROMAP (1<<0)
>
> + u32 ggtt_alignment;
> +
> struct intel_context {
> struct drm_i915_gem_object *state;
> struct intel_ringbuffer *ringbuf;
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index a3b11aac23a4..c620fe6c9d96 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -268,6 +268,8 @@ __create_hw_context(struct drm_device *dev,
> list_add_tail(&ctx->link, &dev_priv->context_list);
> ctx->i915 = dev_priv;
>
> + ctx->ggtt_alignment = get_context_alignment(dev_priv);
> +
> if (dev_priv->hw_context_size) {
> struct drm_i915_gem_object *obj =
> i915_gem_alloc_context_obj(dev, dev_priv->hw_context_size);
> @@ -413,26 +415,6 @@ int i915_gem_context_init(struct drm_device *dev)
> return PTR_ERR(ctx);
> }
>
> - if (!i915.enable_execlists && ctx->engine[RCS].state) {
> - int ret;
> -
> - /* We may need to do things with the shrinker which
> - * require us to immediately switch back to the default
> - * context. This can cause a problem as pinning the
> - * default context also requires GTT space which may not
> - * be available. To avoid this we always pin the default
> - * context.
> - */
> - ret = i915_gem_obj_ggtt_pin(ctx->engine[RCS].state,
> - get_context_alignment(dev_priv), 0);
> - if (ret) {
> - DRM_ERROR("Failed to pinned default global context (error %d)\n",
> - ret);
> - i915_gem_context_unreference(ctx);
> - return ret;
> - }
> - }
> -
> dev_priv->kernel_context = ctx;
>
> DRM_DEBUG_DRIVER("%s context support initialized\n",
> @@ -469,9 +451,6 @@ void i915_gem_context_fini(struct drm_device *dev)
>
> lockdep_assert_held(&dev->struct_mutex);
>
> - if (!i915.enable_execlists && dctx->engine[RCS].state)
> - i915_gem_object_ggtt_unpin(dctx->engine[RCS].state);
> -
> i915_gem_context_unreference(dctx);
> dev_priv->kernel_context = NULL;
>
> @@ -721,7 +700,7 @@ static int do_rcs_switch(struct drm_i915_gem_request *req)
>
> /* Trying to pin first makes error handling easier. */
> ret = i915_gem_obj_ggtt_pin(to->engine[RCS].state,
> - get_context_alignment(engine->i915),
> + to->ggtt_alignment,
> 0);
> if (ret)
> return ret;
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 8d35a3978f9b..92bb376e5039 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -2240,6 +2240,47 @@ intel_ringbuffer_free(struct intel_ringbuffer *ring)
> kfree(ring);
> }
>
> +static int intel_ring_context_pin(struct i915_gem_context *ctx,
> + struct intel_engine_cs *engine)
> +{
> + struct intel_context *ce = &ctx->engine[engine->id];
> + int ret;
> +
> + lockdep_assert_held(&ctx->i915->dev->struct_mutex);
> +
> + if (ce->pin_count++)
> + return 0;
> +
> + if (ce->state) {
> + ret = i915_gem_obj_ggtt_pin(ce->state, ctx->ggtt_alignment, 0);
> + if (ret)
> + goto error;
> + }
> +
> + i915_gem_context_reference(ctx);
> + return 0;
> +
> +error:
> + ce->pin_count = 0;
> + return ret;
> +}
> +
> +static void intel_ring_context_unpin(struct i915_gem_context *ctx,
> + struct intel_engine_cs *engine)
> +{
> + struct intel_context *ce = &ctx->engine[engine->id];
> +
> + lockdep_assert_held(&ctx->i915->dev->struct_mutex);
> +
> + if (--ce->pin_count)
> + return;
> +
> + if (ce->state)
> + i915_gem_object_ggtt_unpin(ce->state);
> +
> + i915_gem_context_unreference(ctx);
> +}
> +
> static int intel_init_ring_buffer(struct drm_device *dev,
> struct intel_engine_cs *engine)
> {
> @@ -2260,6 +2301,17 @@ static int intel_init_ring_buffer(struct drm_device *dev,
>
> init_waitqueue_head(&engine->irq_queue);
>
> + /* We may need to do things with the shrinker which
> + * require us to immediately switch back to the default
> + * context. This can cause a problem as pinning the
> + * default context also requires GTT space which may not
> + * be available. To avoid this we always pin the default
> + * context.
> + */
> + ret = intel_ring_context_pin(dev_priv->kernel_context, engine);
> + if (ret)
> + goto error;
> +
> ringbuf = intel_engine_create_ringbuffer(engine, 32 * PAGE_SIZE);
> if (IS_ERR(ringbuf)) {
> ret = PTR_ERR(ringbuf);
> @@ -2327,6 +2379,9 @@ void intel_cleanup_engine(struct intel_engine_cs *engine)
>
> i915_cmd_parser_fini_ring(engine);
> i915_gem_batch_pool_fini(&engine->batch_pool);
> +
> + intel_ring_context_unpin(dev_priv->kernel_context, engine);
> +
> engine->i915 = NULL;
> }
>
> --
> 2.8.1
>
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