Re: [PATCH 4/5] drm/i915: wait render timeout ioctl

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Apr 30, 2012 at 06:41:08PM -0700, Ben Widawsky wrote:
> This helps implement GL_ARB_sync put stops short of allowing full blow
> sync objects.
> 
> Finally we can use the new timed seqno waiting function to allow
> userspace to wait on a request with a timeout. This implements that
> interface.
> 
> The new ioctl is very straight forward, there is a flags field which I
> envision may be useful for various flush permutations of the command.
> 
> v2: ETIME/ERESTARTSYS instead of changing to EBUSY, and EGAIN (Chris)
> Flush the object from the gpu write domain (Chris + Daniel)
> Fix leaked refcount in good case (Chris)
> Naturally align ioctl struct (Chris)
> 
> v3: Drop lock after getting seqno to avoid ugly dance (Chris)
> 
> v4: check for 0 timeout after olr check to allow polling (Chris)
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_dma.c |    1 +
>  drivers/gpu/drm/i915/i915_drv.h |    2 ++
>  drivers/gpu/drm/i915/i915_gem.c |   63 +++++++++++++++++++++++++++++++++++++++
>  include/drm/i915_drm.h          |    8 +++++
>  4 files changed, 74 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 17081da..97a8f02 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -2186,6 +2186,7 @@ struct drm_ioctl_desc i915_ioctls[] = {
>  	DRM_IOCTL_DEF_DRV(I915_OVERLAY_ATTRS, intel_overlay_attrs, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
>  	DRM_IOCTL_DEF_DRV(I915_SET_SPRITE_COLORKEY, intel_sprite_set_colorkey, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
>  	DRM_IOCTL_DEF_DRV(I915_GET_SPRITE_COLORKEY, intel_sprite_get_colorkey, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
> +	DRM_IOCTL_DEF_DRV(I915_GEM_WAIT, i915_gem_wait_ioctl, DRM_UNLOCKED),
>  };
>  
>  int i915_max_ioctl = DRM_ARRAY_SIZE(i915_ioctls);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index ca13098..dd8b33f 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1220,6 +1220,8 @@ int i915_gem_get_tiling(struct drm_device *dev, void *data,
>  			struct drm_file *file_priv);
>  int i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
>  				struct drm_file *file_priv);
> +int i915_gem_wait_ioctl(struct drm_device *dev, void *data,
> +			struct drm_file *file_priv);
>  void i915_gem_load(struct drm_device *dev);
>  int i915_gem_init_object(struct drm_gem_object *obj);
>  int __must_check i915_gem_flush_ring(struct intel_ring_buffer *ring,
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 8f19cc1..cf3e506 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1997,6 +1997,69 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj)
>  	return 0;
>  }
>  
> +int
> +i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
> +{
> +	struct drm_i915_gem_wait *args = data;
> +	struct drm_i915_gem_object *obj;
> +	struct intel_ring_buffer *ring = NULL;
> +	struct timespec timeout;
> +	u32 seqno = 0;
> +	int ret = 0;
> +
> +	timeout = ns_to_timespec(args->timeout_ns);
> +
> +	ret = i915_mutex_lock_interruptible(dev);
> +	if (ret)
> +		return ret;
> +
> +	obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->bo_handle));
> +	if (&obj->base == NULL) {
> +		mutex_unlock(&dev->struct_mutex);
> +		return -ENOENT;
> +	}
> +
> +	/* Need to make sure the object is flushed first. This non-obvious
> +	 * flush is required to enforce that (active && !olr) == no wait
> +	 * necessary.
> +	 */
> +	ret = i915_gem_object_flush_gpu_write_domain(obj);
> +	if (ret)
> +		goto out;
> +
> +	if (obj->active) {
> +		seqno = obj->last_rendering_seqno;
> +		ring = obj->ring;
> +	}
> +
> +	if (seqno == 0)
> +		 goto out;
> +
> +	ret = i915_gem_check_olr(ring, seqno);
> +	if (ret)
> +		goto out;
> +
> +	/* Do this after OLR check to make sure we make forward progress polling
> +	 * on this IOCTL with a 0 timeout (like busy ioctl)
> +	 */
> +	if (!args->timeout_ns) {
> +		ret = -EBUSY;

This return value is a bit inconsitency with the case where we have
timeout_ns > 0 but time out. I think we should return the same -ETIME in
both cases.
-Daniel
> +		goto out;
> +	}
> +
> +	drm_gem_object_unreference(&obj->base);
> +	mutex_unlock(&dev->struct_mutex);
> +
> +	ret = __wait_seqno(ring, seqno, true, &timeout);
> +	args->timeout_ns = timespec_to_ns(&timeout);
> +	return ret;
> +
> +out:
> +	drm_gem_object_unreference(&obj->base);
> +	mutex_unlock(&dev->struct_mutex);
> +	return ret;
> +}
> +
>  /**
>   * i915_gem_object_sync - sync an object to a ring.
>   *
> diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
> index f3f8224..8f818f8 100644
> --- a/include/drm/i915_drm.h
> +++ b/include/drm/i915_drm.h
> @@ -200,6 +200,7 @@ typedef struct _drm_i915_sarea {
>  #define DRM_I915_GEM_EXECBUFFER2	0x29
>  #define DRM_I915_GET_SPRITE_COLORKEY	0x2a
>  #define DRM_I915_SET_SPRITE_COLORKEY	0x2b
> +#define DRM_I915_GEM_WAIT	0x2c
>  
>  #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
>  #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
> @@ -243,6 +244,7 @@ typedef struct _drm_i915_sarea {
>  #define DRM_IOCTL_I915_OVERLAY_ATTRS	DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_OVERLAY_ATTRS, struct drm_intel_overlay_attrs)
>  #define DRM_IOCTL_I915_SET_SPRITE_COLORKEY DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_SET_SPRITE_COLORKEY, struct drm_intel_sprite_colorkey)
>  #define DRM_IOCTL_I915_GET_SPRITE_COLORKEY DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_SET_SPRITE_COLORKEY, struct drm_intel_sprite_colorkey)
> +#define DRM_IOCTL_I915_GEM_WAIT		DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_GEM_WAIT, struct drm_i915_gem_wait)
>  
>  /* Allow drivers to submit batchbuffers directly to hardware, relying
>   * on the security mechanisms provided by hardware.
> @@ -886,4 +888,10 @@ struct drm_intel_sprite_colorkey {
>  	__u32 flags;
>  };
>  
> +struct drm_i915_gem_wait {
> +	__u32 bo_handle;
> +	__u32 flags;
> +	__u64 timeout_ns;
> +};
> +
>  #endif				/* _I915_DRM_H_ */
> -- 
> 1.7.10
> 
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-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48