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* [PATCH] drm/vblank: Fix vblank timestamp debugs
@ 2017-11-13 15:02 Ville Syrjala
  2017-11-13 15:16 ` Arnd Bergmann
  0 siblings, 1 reply; 2+ messages in thread
From: Ville Syrjala @ 2017-11-13 15:02 UTC (permalink / raw)
  To: dri-devel; +Cc: Dave Airlie, Keith Packard, Arnd Bergmann

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

We're currently calling ktime_to_timespec64() on stack garbage
hence the debug output for vblank timestamps also contains garbage.
Let's assing something to the ktime_t first before we go converting
it to a timespec.

While at it micro-optimize the ktime_to_timespec64() calls away
when vblank debugging isn't enabled.

Fixes: 67680d3c0464 ("drm: vblank: use ktime_t instead of timeval")
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Keith Packard <keithp@keithp.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/drm_vblank.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 09c1c4ff93ca..2c68909637b5 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -664,14 +664,16 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 	delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),
 			   mode->crtc_clock);
 
-	/* save this only for debugging purposes */
-	ts_etime = ktime_to_timespec64(etime);
-	ts_vblank_time = ktime_to_timespec64(*vblank_time);
 	/* Subtract time delta from raw timestamp to get final
 	 * vblank_time timestamp for end of vblank.
 	 */
-	etime = ktime_sub_ns(etime, delta_ns);
-	*vblank_time = etime;
+	*vblank_time = ktime_sub_ns(etime, delta_ns);
+
+	if ((drm_debug & DRM_UT_VBL) == 0)
+		return true;
+
+	ts_etime = ktime_to_timespec64(etime);
+	ts_vblank_time = ktime_to_timespec64(*vblank_time);
 
 	DRM_DEBUG_VBL("crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n",
 		      pipe, hpos, vpos,
-- 
2.13.6

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^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] drm/vblank: Fix vblank timestamp debugs
  2017-11-13 15:02 [PATCH] drm/vblank: Fix vblank timestamp debugs Ville Syrjala
@ 2017-11-13 15:16 ` Arnd Bergmann
  0 siblings, 0 replies; 2+ messages in thread
From: Arnd Bergmann @ 2017-11-13 15:16 UTC (permalink / raw)
  To: Ville Syrjala; +Cc: Dave Airlie, Keith Packard, dri-devel

On Mon, Nov 13, 2017 at 4:02 PM, Ville Syrjala
<ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> We're currently calling ktime_to_timespec64() on stack garbage
> hence the debug output for vblank timestamps also contains garbage.
> Let's assing something to the ktime_t first before we go converting
> it to a timespec.
>
> While at it micro-optimize the ktime_to_timespec64() calls away
> when vblank debugging isn't enabled.
>
> Fixes: 67680d3c0464 ("drm: vblank: use ktime_t instead of timeval")

Acked-by: Arnd Bergmann <arnd@arndb.de>

Sorry about the mess and thanks for cleaning up behind me.

       Arnd
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dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2017-11-13 15:02 [PATCH] drm/vblank: Fix vblank timestamp debugs Ville Syrjala
2017-11-13 15:16 ` Arnd Bergmann

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