Re: [PATCH 3/3] intel: wait render timeout implementation

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jun 05, 2012 at 03:43:07PM -0700, Ben Widawsky wrote:
> int drm_intel_gem_bo_wait(drm_intel_bo *bo, uint64_t timeout_ns)
> 
> This should bump the libdrm version. We're waiting for context support
> so we can do both features in one bump.
> 
> v2: don't return remaining timeout amount
> use get param and fallback for older kernels
> 
> v3: only doing getparam at init
> prototypes now have a signed input value
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

Let's bikeshed this some more ;-)
- I think a quick comment to say that negative timeouts result in a
  infinite wait would be nice.
- If we want to keep timeout=0 means polling, you need to add a special
  case in the fallback to check for that and call the busy ioctl instead
  (and remap the business value to the correct return value).
- iirc drmIoctl doesn't return the kernels -ERRNO value in it's retval
  (and shovels it into errno instead). I think undoing that suckiness
  would be good, so that we return -ETIME if the timer expired.

Yours, Daniel
> ---
>  intel/intel_bufmgr.h     |    1 +
>  intel/intel_bufmgr_gem.c |   30 ++++++++++++++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/intel/intel_bufmgr.h b/intel/intel_bufmgr.h
> index c197abc..fa6c4dd 100644
> --- a/intel/intel_bufmgr.h
> +++ b/intel/intel_bufmgr.h
> @@ -184,6 +184,7 @@ int drm_intel_get_pipe_from_crtc_id(drm_intel_bufmgr *bufmgr, int crtc_id);
>  
>  int drm_intel_get_aperture_sizes(int fd, size_t *mappable, size_t *total);
>  int drm_intel_bufmgr_gem_get_devid(drm_intel_bufmgr *bufmgr);
> +int drm_intel_gem_bo_wait(drm_intel_bo *bo, int64_t timeout_ns);
>  
>  /* drm_intel_bufmgr_fake.c */
>  drm_intel_bufmgr *drm_intel_bufmgr_fake_init(int fd,
> diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
> index b776d2f..048fca7 100644
> --- a/intel/intel_bufmgr_gem.c
> +++ b/intel/intel_bufmgr_gem.c
> @@ -119,6 +119,7 @@ typedef struct _drm_intel_bufmgr_gem {
>  	unsigned int has_blt : 1;
>  	unsigned int has_relaxed_fencing : 1;
>  	unsigned int has_llc : 1;
> +	unsigned int has_wait_timeout : 1;
>  	unsigned int bo_reuse : 1;
>  	unsigned int no_exec : 1;
>  	bool fenced_relocs;
> @@ -1479,6 +1480,31 @@ drm_intel_gem_bo_wait_rendering(drm_intel_bo *bo)
>  }
>  
>  /**
> + * Same as drm_intel_gem_bo_wait_rendering except a timeout parameter allows the
> + * operation to give up after a certain amount of time.
> + *
> + * A 0 return value implies that the wait was successful. Otherwise some
> + * negative return value describes the error.
> + */
> +int drm_intel_gem_bo_wait(drm_intel_bo *bo, int64_t timeout_ns)
> +{
> +	drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *) bo->bufmgr;
> +	drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *) bo;
> +	struct drm_i915_gem_wait wait;
> +	int ret;
> +
> +	if (!bufmgr_gem->has_wait_timeout) {
> +		drm_intel_gem_bo_wait_rendering(bo);
> +		return 0;
> +	}
> +
> +	wait.bo_handle = bo_gem->gem_handle;
> +	wait.timeout_ns = timeout_ns;
> +	wait.flags = 0;
> +	return drmIoctl(bufmgr_gem->fd, DRM_IOCTL_I915_GEM_WAIT, &wait);
> +}
> +
> +/**
>   * Sets the object to the GTT read and possibly write domain, used by the X
>   * 2D driver in the absence of kernel support to do drm_intel_gem_bo_map_gtt().
>   *
> @@ -2898,6 +2924,10 @@ drm_intel_bufmgr_gem_init(int fd, int batch_size)
>  	ret = drmIoctl(bufmgr_gem->fd, DRM_IOCTL_I915_GETPARAM, &gp);
>  	bufmgr_gem->has_relaxed_fencing = ret == 0;
>  
> +	gp.param = I915_PARAM_HAS_WAIT_TIMEOUT;
> +	ret = drmIoctl(bufmgr_gem->fd, DRM_IOCTL_I915_GETPARAM, &gp);
> +	bufmgr_gem->has_wait_timeout = ret == 0;
> +
>  	gp.param = I915_PARAM_HAS_LLC;
>  	ret = drmIoctl(bufmgr_gem->fd, DRM_IOCTL_I915_GETPARAM, &gp);
>  	if (ret != 0) {
> -- 
> 1.7.10.3
> 
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-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48