On Sun, 15 Jul 2012 12:34:24 +0100
Chris Wilson <ch...@chris-wilson.co.uk> wrote:

> When bug hunting, I found the interface to do_switch() overly
> complicated and I believe festered the earlier bug. This aims to make
> the code a little clearer.

Would you be willing to split this up into 2 patches? One which
reorganizes create_default, and one which changes do_switch?

> 
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Ben Widawsky <b...@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_gem_context.c |   57 
> ++++++++++++++-----------------
>  1 file changed, 26 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c 
> b/drivers/gpu/drm/i915/i915_gem_context.c
> index 0cfc9d2..90a9c9e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -97,8 +97,7 @@
>  
>  static struct i915_hw_context *
>  i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id);
> -static int do_switch(struct drm_i915_gem_object *from_obj,
> -                  struct i915_hw_context *to, u32 seqno);
> +static int do_switch(struct i915_hw_context *to);
>  
>  static int get_context_size(struct drm_device *dev)
>  {
> @@ -220,19 +219,20 @@ static int create_default_context(struct 
> drm_i915_private *dev_priv)
>        */
>       dev_priv->ring[RCS].default_context = ctx;
>       ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false);
> -     if (ret) {
> -             do_destroy(ctx);
> -             return ret;
> -     }
> +     if (ret)
> +             goto err_destroy;
>  
> -     ret = do_switch(NULL, ctx, 0);
> -     if (ret) {
> -             i915_gem_object_unpin(ctx->obj);
> -             do_destroy(ctx);
> -     } else {
> -             DRM_DEBUG_DRIVER("Default HW context loaded\n");
> -     }
> +     ret = do_switch(ctx);
> +     if (ret)
> +             goto err_unpin;
>  
> +     DRM_DEBUG_DRIVER("Default HW context loaded\n");
> +     return 0;
> +
> +err_unpin:
> +     i915_gem_object_unpin(ctx->obj);
> +err_destroy:
> +     do_destroy(ctx);
>       return ret;
>  }
>  
> @@ -359,17 +359,18 @@ mi_set_context(struct intel_ring_buffer *ring,
>       return ret;
>  }
>  
> -static int do_switch(struct drm_i915_gem_object *from_obj,
> -                  struct i915_hw_context *to,
> -                  u32 seqno)
> +static int do_switch(struct i915_hw_context *to)
>  {
> -     struct intel_ring_buffer *ring = NULL;
> +     struct intel_ring_buffer *ring = to->ring;
> +     struct drm_i915_gem_object *from_obj = ring->last_context_obj;
>       u32 hw_flags = 0;
>       int ret;
>  
> -     BUG_ON(to == NULL);
>       BUG_ON(from_obj != NULL && from_obj->pin_count == 0);
>  
> +     if (from_obj == to->obj)
> +             return 0;
> +
>       ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false);
>       if (ret)
>               return ret;
> @@ -389,7 +390,6 @@ static int do_switch(struct drm_i915_gem_object *from_obj,
>       else if (WARN_ON_ONCE(from_obj == to->obj)) /* not yet expected */
>               hw_flags |= MI_FORCE_RESTORE;
>  
> -     ring = to->ring;
>       ret = mi_set_context(ring, to, hw_flags);
>       if (ret) {
>               i915_gem_object_unpin(to->obj);
> @@ -403,6 +403,7 @@ static int do_switch(struct drm_i915_gem_object *from_obj,
>        * MI_SET_CONTEXT instead of when the next seqno has completed.
>        */
>       if (from_obj != NULL) {
> +             u32 seqno = i915_gem_next_request_seqno(ring);
>               from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
>               i915_gem_object_move_to_active(from_obj, ring, seqno);
>               /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the
> @@ -413,7 +414,7 @@ static int do_switch(struct drm_i915_gem_object *from_obj,
>                * swapped, but there is no way to do that yet.
>                */
>               from_obj->dirty = 1;
> -             BUG_ON(from_obj->ring != to->ring);
> +             BUG_ON(from_obj->ring != ring);
>               i915_gem_object_unpin(from_obj);
>  
>               drm_gem_object_unreference(&from_obj->base);
> @@ -444,10 +445,7 @@ int i915_switch_context(struct intel_ring_buffer *ring,
>                       int to_id)
>  {
>       struct drm_i915_private *dev_priv = ring->dev->dev_private;
> -     struct drm_i915_file_private *file_priv = NULL;
>       struct i915_hw_context *to;
> -     struct drm_i915_gem_object *from_obj = ring->last_context_obj;
> -     int ret;
>  
>       if (dev_priv->hw_contexts_disabled)
>               return 0;
> @@ -455,21 +453,18 @@ int i915_switch_context(struct intel_ring_buffer *ring,
>       if (ring != &dev_priv->ring[RCS])
>               return 0;
>  
> -     if (file)
> -             file_priv = file->driver_priv;
> -
>       if (to_id == DEFAULT_CONTEXT_ID) {
>               to = ring->default_context;
>       } else {
> -             to = i915_gem_context_get(file_priv, to_id);
> +             if (file == NULL)
> +                     return -EINVAL;
> +
> +             to = i915_gem_context_get(file->driver_priv, to_id);
>               if (to == NULL)
>                       return -ENOENT;
>       }
>  
> -     if (from_obj == to->obj)
> -             return 0;
> -
> -     return do_switch(from_obj, to, i915_gem_next_request_seqno(to->ring));
> +     return do_switch(to);
>  }
>  
>  int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,



-- 
Ben Widawsky, Intel Open Source Technology Center
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