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Commit 23ba4fd0 authored by Ben Widawsky's avatar Ben Widawsky Committed by Daniel Vetter
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drm/i915: wait render timeout ioctl 



This helps implement GL_ARB_sync but stops short of allowing full blown
sync objects. Finally we can use the new timed seqno waiting function
to allow userspace to wait on a buffer object with a timeout. This
implements that interface.

The IOCTL will take as input a buffer object handle, and a timeout in
nanoseconds (flags is currently optional but will likely be used for
permutations of flush operations). Users may specify 0 nanoseconds to
instantly check.

The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
non-zero timeout parameter the wait ioctl will wait for the given number
of nanoseconds on an object becoming unbusy. Since the wait itself does
so holding struct_mutex the object may become re-busied before this
completes. A similar but shorter race condition exists in the busy
ioctl.

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)

v5: Updated the comment. (Chris)

v6: Return -ETIME instead of -EBUSY when timeout_ns is 0 (Daniel)
Fix the commit message comment to be less ugly (Ben)
Add a warning to check the return timespec (Ben)

v7: Use DRM_AUTH for the ioctl. (Eugeni)

Signed-off-by: default avatarBen Widawsky <ben@bwidawsk.net>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent f3fd3768

drivers/gpu/drm/i915/i915_dma.c

+1 −0
Original line number Diff line number Diff line
@@ -1803,6 +1803,7 @@ 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_AUTH|DRM_UNLOCKED),

};



int i915_max_ioctl = DRM_ARRAY_SIZE(i915_ioctls);

drivers/gpu/drm/i915/i915_drv.h

+2 −0
Original line number Diff line number Diff line
@@ -1229,6 +1229,8 @@ 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,

drivers/gpu/drm/i915/i915_gem.c

+86 −0
Original line number Diff line number Diff line
@@ -2000,6 +2000,92 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj) 
	return 0;

}



/**

 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT

 * @DRM_IOCTL_ARGS: standard ioctl arguments

 *

 * Returns 0 if successful, else an error is returned with the remaining time in

 * the timeout parameter.

 *  -ETIME: object is still busy after timeout

 *  -ERESTARTSYS: signal interrupted the wait

 *  -ENONENT: object doesn't exist

 * Also possible, but rare:

 *  -EAGAIN: GPU wedged

 *  -ENOMEM: damn

 *  -ENODEV: Internal IRQ fail

 *  -E?: The add request failed

 *

 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any

 * non-zero timeout parameter the wait ioctl will wait for the given number of

 * nanoseconds on an object becoming unbusy. Since the wait itself does so

 * without holding struct_mutex the object may become re-busied before this

 * function completes. A similar but shorter * race condition exists in the busy

 * ioctl

 */

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 = -ETIME;

		goto out;

	}



	drm_gem_object_unreference(&obj->base);

	mutex_unlock(&dev->struct_mutex);



	ret = __wait_seqno(ring, seqno, true, &timeout);

	WARN_ON(!timespec_valid(&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.

 *

include/drm/i915_drm.h

+10 −0
Original line number Diff line number Diff line
@@ -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 +888,12 @@ struct drm_intel_sprite_colorkey { 
	__u32 flags;

};



struct drm_i915_gem_wait {

	/** Handle of BO we shall wait on */

	__u32 bo_handle;

	__u32 flags;

	/** Number of nanoseconds to wait, Returns time remaining. */

	__u64 timeout_ns;

};



#endif				/* _I915_DRM_H_ */