Re: [PATCH] Revert "intel: Fix documentation for drm_intel_gem_bo_wait()"

[Dave Gordon <david.s.gordon@intel.com>]

On 06/03/15 17:58, Daniel Vetter wrote:
> This reverts commit 080b4929b7452dc1fea32ac1d32e7e571e7fb38b.
> 
> Chris noticed that "negative values wait forever" is indeed intended
> behaviour and the issue is just that we didn't have a testcase (fixed
> now) and that a regression slipped through (fixed and on track for all
> stable kernels).
> 
> So lets undo the documentation change for consistency, since working
> around kernel regressions isn't good. Practical impact is nil anyway.
> 
> v2: Add a note to docs that some kernels have been broken.
> 
> v3: Remove the random garbage included by accident.
> 
> Cc: Kristian Høgsberg <krh@bitplanet.net>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  intel/intel_bufmgr_gem.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
> index 33d8fbc46242..acbfd4ada209 100644
> --- a/intel/intel_bufmgr_gem.c
> +++ b/intel/intel_bufmgr_gem.c
> @@ -1655,14 +1655,12 @@ drm_intel_gem_bo_wait_rendering(drm_intel_bo *bo)
>   *
>   * @bo: buffer object to wait for
>   * @timeout_ns: amount of time to wait in nanoseconds.
> - *   If value is less than or equal to 0, return immediately.
> + *   If value is less than 0, an infinite wait will occur.
>   *
> - * Returns 0 if the wait was successful ie. the last batch referencing
> - * the object has completed within the allotted time. Otherwise some
> - * negative return value describes the error. Of particular interest
> - * is -ETIME when the wait has failed to yield the desired result.
> - * Use a timeout of INT64_MAX to wait indefinitely (well, at least 292
> - * years).
> + * Returns 0 if the wait was successful ie. the last batch referencing the
> + * object has completed within the allotted time. Otherwise some negative return
> + * value describes the error. Of particular interest is -ETIME when the wait has
> + * failed to yield the desired result.
>   *
>   * Similar to drm_intel_gem_bo_wait_rendering except a timeout parameter allows
>   * the operation to give up after a certain amount of time. Another subtle
> @@ -1675,6 +1673,9 @@ drm_intel_gem_bo_wait_rendering(drm_intel_bo *bo)
>   * not guarantee that the buffer is re-issued via another thread, or an flinked
>   * handle. Userspace must make sure this race does not occur if such precision
>   * is important.
> + *
> + * Note that some kernels have broken the inifite wait for negative values

s/inifite/infinite/, then

Reviewed-by: Dave Gordon <david.s.gordon@intel.com>

> + * promise, upgrade to latest stable kernels if this is the case.
>   */
>  drm_public int
>  drm_intel_gem_bo_wait(drm_intel_bo *bo, int64_t timeout_ns)
> 

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