4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
commit 89cf83d4e065ff9fbd2ddc674489c8058eeca758 upstream.
We wait upon jiffies, but report the time elapsed using a
high-resolution timer. This discrepancy can lead to us timing out the
wait prior to us reporting the elapsed time as complete.
This restores the squelching lost in commit e95433c73a11 ("drm/i915:
Rearrange i915_wait_request() accounting with callers").
Fixes: e95433c73a11 ("drm/i915: Rearrange i915_wait_request() accounting with callers")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.william.auld@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: <drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx> # v4.10-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/20170216125441.30923-1-chris@xxxxxxxxxxxxxxxxxx
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
(cherry picked from commit c1d2061b28c2aa25ec39b60d9c248e6beebd7315)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3003,6 +3003,16 @@ i915_gem_wait_ioctl(struct drm_device *d
args->timeout_ns -= ktime_to_ns(ktime_sub(ktime_get(), start));
if (args->timeout_ns < 0)
args->timeout_ns = 0;
+
+ /*
+ * Apparently ktime isn't accurate enough and occasionally has a
+ * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch
+ * things up to make the test happy. We allow up to 1 jiffy.
+ *
+ * This is a regression from the timespec->ktime conversion.
+ */
+ if (ret == -ETIME && !nsecs_to_jiffies(args->timeout_ns))
+ args->timeout_ns = 0;
}
i915_gem_object_put(obj);