From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> [ 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@xxxxxxxx> Cc: Keith Packard <keithp@xxxxxxxxxx> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx> Cc: Dave Airlie <airlied@xxxxxxxxxx> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20171113150210.11311-1-ville.syrjala@xxxxxxxxxxxxxxx Acked-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- 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 3717b3df34a4..32d9bcf5be7f 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -663,14 +663,16 @@ 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, -- 2.14.1