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drm: use monotonic time in drm_calc_vbltimestamp_from_scanoutpos

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For measuring duration we want to avoid that our start/end timestamps
jump, so use monotonic instead of real time for that.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: mario.kleiner
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Imre Deak 2012-10-23 18:53:25 +00:00 committed by Dave Airlie
parent 11e686855c
commit e62f2f5acb
1 changed files with 12 additions and 6 deletions
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18
drivers/gpu/drm/drm_irq.c
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@ -576,7 +576,8 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
unsigned flags,
struct drm_crtc *refcrtc)
{
struct timeval stime, raw_time;
ktime_t stime, etime, mono_time_offset;
struct timeval tv_etime;
struct drm_display_mode *mode;
int vbl_status, vtotal, vdisplay;
int vpos, hpos, i;
@ -625,13 +626,14 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
preempt_disable();
/* Get system timestamp before query. */
do_gettimeofday(&stime);
stime = ktime_get();
/* Get vertical and horizontal scanout pos. vpos, hpos. */
vbl_status = dev->driver->get_scanout_position(dev, crtc, &vpos, &hpos);
/* Get system timestamp after query. */
do_gettimeofday(&raw_time);
etime = ktime_get();
mono_time_offset = ktime_get_monotonic_offset();
preempt_enable();
@ -642,7 +644,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
return -EIO;
}
duration_ns = timeval_to_ns(&raw_time) - timeval_to_ns(&stime);
duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
/* Accept result with < max_error nsecs timing uncertainty. */
if (duration_ns <= (s64) *max_error)
@ -689,14 +691,18 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
vbl_status |= 0x8;
}
etime = ktime_sub(etime, mono_time_offset);
/* save this only for debugging purposes */
tv_etime = ktime_to_timeval(etime);
/* Subtract time delta from raw timestamp to get final
* vblank_time timestamp for end of vblank.
*/
*vblank_time = ns_to_timeval(timeval_to_ns(&raw_time) - delta_ns);
etime = ktime_sub_ns(etime, delta_ns);
*vblank_time = ktime_to_timeval(etime);
DRM_DEBUG("crtc %d : v %d p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
crtc, (int)vbl_status, hpos, vpos,
(long)raw_time.tv_sec, (long)raw_time.tv_usec,
(long)tv_etime.tv_sec, (long)tv_etime.tv_usec,
(long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
(int)duration_ns/1000, i);