Previously, ms_flush_drm_events() returned a boolean value, and it was
very easy to interpret the meaning incorrectly. Now, we return an
integer value.
The possible outcomes of this call are:
- poll() raised an error (formerly TRUE, now -1 - poll's return value)
- poll() said there are no events (formerly TRUE, now 0).
- drmHandleEvent() raised an error (formerly FALSE, now the negative
value returned by drmHandleEvent).
- An event was successfully handled (formerly TRUE, now 1).
The nice part is that this allows you to distinguish errors (< 0),
nothing to do (= 0), and success (1). We no longer conflate errors
with success.
v2: Change ms_present_queue_vblank to < 0 instead of <= 0, fixing an
unintentional behavior change. libdrm may return EBUSY if it's
received EINTR for more than a second straight; just keep retrying
in that case. Suggested by Jasper St. Pierre.
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
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