Re: [Intel-gfx] [PATCH v2 1/2] drm/atomic: move waiting for hw_done to a helper

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jun 14, 2017 at 08:11:18PM +0200, Maarten Lankhorst wrote:
> Op 14-06-17 om 16:52 schreef Ville Syrjälä:
> > On Wed, Jun 14, 2017 at 11:08:41AM +0200, Maarten Lankhorst wrote:
> >> Moving the wait to a helper allows callers outside of the core to
> >> wait for pending updates to complete.
> >>
> >> This can be used to prevent races against nonblocking modesets.
> >> Only the hw_done call in swap_state is moved to a helper, doing
> >> it for the other callers requires too many changes and I think this
> >> is the only useful one to export.
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> >> ---
> >>  drivers/gpu/drm/drm_atomic_helper.c | 51 +++++++++++++++++++++++++++----------
> >>  include/drm/drm_atomic_helper.h     |  1 +
> >>  2 files changed, 38 insertions(+), 14 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> >> index 86d3093c6c9b..1b068ce1aea9 100644
> >> --- a/drivers/gpu/drm/drm_atomic_helper.c
> >> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> >> @@ -2067,6 +2067,41 @@ void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
> >>  EXPORT_SYMBOL(drm_atomic_helper_cleanup_planes);
> >>  
> >>  /**
> >> + * drm_atomic_helper_wait_for_hw_done - wait for all previous hw updates to complete.
> >> + * @crtc: crtc to wait on.
> >> + *
> >> + * This function waits for all previous hardware updates queued on @crtc
> >> + * to complete.
> >> + *
> >> + * Returns:
> >> + * 0 on success, negative error code on failure.
> >> + */
> >> +int drm_atomic_helper_wait_for_hw_done(struct drm_crtc *crtc)
> >> +{
> >> +	struct drm_crtc_commit *commit;
> >> +	long ret;
> >> +
> >> +	spin_lock(&crtc->commit_lock);
> >> +	commit = list_first_entry_or_null(&crtc->commit_list,
> >> +			struct drm_crtc_commit, commit_entry);
> >> +	if (commit)
> >> +		drm_crtc_commit_get(commit);
> >> +	spin_unlock(&crtc->commit_lock);
> >> +
> >> +	if (!commit)
> >> +		return 0;
> >> +
> >> +	ret = wait_for_completion_timeout(&commit->hw_done, 10 * HZ);
> >> +	drm_crtc_commit_put(commit);
> >> +
> >> +	if (ret == 0)
> >> +		return -EBUSY;
> > -ETIMEDOUT ?
> ETIMEDOUT -> /* Connection timed out */

It's the standard "something timed out" errno. Used all over drm.

> 
> No I don't think that would match.

-- 
Ville Syrjälä
Intel OTC
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