From c61eef726a78ae77b6ce223d01ea2130f465fe5c Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Tue, 23 Oct 2012 18:53:26 +0000 Subject: drm: add support for monotonic vblank timestamps Jumps in the vblank and page flip event timestamps cause trouble for clients, so we should avoid them. The timestamp we get currently with gettimeofday can jump, so use instead monotonic timestamps. For backward compatibility use a module flag to revert back to using gettimeofday timestamps. Add also a DRM_CAP_TIMESTAMP_MONOTONIC flag that is simply a read only version of the module flag, so that clients can query this without depending on sysfs. Signed-off-by: Imre Deak Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_ioctl.c | 3 +++ drivers/gpu/drm/drm_irq.c | 25 ++++++++++++++++++++----- drivers/gpu/drm/drm_stub.c | 8 ++++++++ 3 files changed, 31 insertions(+), 5 deletions(-) (limited to 'drivers/gpu') diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 23dd975..e77bd8b 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -287,6 +287,9 @@ int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv) req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0; req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0; break; + case DRM_CAP_TIMESTAMP_MONOTONIC: + req->value = drm_timestamp_monotonic; + break; default: return -EINVAL; } diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index ef5b5f7..c0f0046 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -633,7 +633,8 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc, /* Get system timestamp after query. */ etime = ktime_get(); - mono_time_offset = ktime_get_monotonic_offset(); + if (!drm_timestamp_monotonic) + mono_time_offset = ktime_get_monotonic_offset(); preempt_enable(); @@ -691,7 +692,9 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc, vbl_status |= 0x8; } - etime = ktime_sub(etime, mono_time_offset); + if (!drm_timestamp_monotonic) + 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 @@ -714,6 +717,17 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc, } EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos); +static struct timeval get_drm_timestamp(void) +{ + ktime_t now; + + now = ktime_get(); + if (!drm_timestamp_monotonic) + now = ktime_sub(now, ktime_get_monotonic_offset()); + + return ktime_to_timeval(now); +} + /** * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent * vblank interval. @@ -751,9 +765,9 @@ u32 drm_get_last_vbltimestamp(struct drm_device *dev, int crtc, } /* GPU high precision timestamp query unsupported or failed. - * Return gettimeofday timestamp as best estimate. + * Return current monotonic/gettimeofday timestamp as best estimate. */ - do_gettimeofday(tvblank); + *tvblank = get_drm_timestamp(); return 0; } @@ -842,7 +856,8 @@ void drm_send_vblank_event(struct drm_device *dev, int crtc, seq = drm_vblank_count_and_time(dev, crtc, &now); } else { seq = 0; - do_gettimeofday(&now); + + now = get_drm_timestamp(); } send_vblank_event(dev, e, seq, &now); } diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c index 6fcdd8e..200e104 100644 --- a/drivers/gpu/drm/drm_stub.c +++ b/drivers/gpu/drm/drm_stub.c @@ -46,16 +46,24 @@ EXPORT_SYMBOL(drm_vblank_offdelay); unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */ EXPORT_SYMBOL(drm_timestamp_precision); +/* + * Default to use monotonic timestamps for wait-for-vblank and page-flip + * complete events. + */ +unsigned int drm_timestamp_monotonic = 1; + MODULE_AUTHOR(CORE_AUTHOR); MODULE_DESCRIPTION(CORE_DESC); MODULE_LICENSE("GPL and additional rights"); MODULE_PARM_DESC(debug, "Enable debug output"); MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]"); MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]"); +MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps"); module_param_named(debug, drm_debug, int, 0600); module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600); module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600); +module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600); struct idr drm_minors_idr; -- cgit v1.1