[PATCH 4.15 053/128] drm/vblank: Fix vblank timestamp debugs

Greg Kroah-Hartman
2018-03-16T15:23:14Z

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4.15-stable review patch. If anyone has any objections, please let me know.

------------------

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

[ Upstream commit bcbec31ce500fe036f75a19bca5c73bfa6dd420b ]

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 SyrjÃ¤lÃ¤ <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171113150210.11311-1-ville.syrjala@linux.intel.com
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/drm_vblank.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -663,14 +663,16 @@ bool drm_calc_vbltimestamp_from_scanoutp
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,