From: Arnd Bergmann Date: Wed, 11 Oct 2017 17:20:13 +0200 Subject: drm: vblank: remove drm_timestamp_monotonic parameter Git-commit: 25e1a79874eb3821d93310c908cc0a81b47af060 Patch-mainline: v4.15-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 There is a risk of overflowing vblank timestamps in 2038 or 2106 if someone sets the drm_timestamp_monotonic module parameter to zero. I found no indication of anyone ever setting the parameter, or complaining about the default being wrong, after it was introduced as a way to handle backwards-compatibility with linux prior to c61eef726a78 ("drm: add support for monotonic vblank timestamps"), so it's probably safer to just remove the parameter completely and only allowing the default behavior. Signed-off-by: Arnd Bergmann Acked-by: Daniel Stone Signed-off-by: Dave Airlie Acked-by: Petr Tesarik --- drivers/gpu/drm/drm_internal.h | 1 - drivers/gpu/drm/drm_ioctl.c | 2 +- drivers/gpu/drm/drm_vblank.c | 29 ++++++----------------------- 3 files changed, 7 insertions(+), 25 deletions(-) --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -55,7 +55,6 @@ int drm_clients_info(struct seq_file *m, int drm_gem_name_info(struct seq_file *m, void *data); /* drm_vblank.c */ -extern unsigned int drm_timestamp_monotonic; void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe); void drm_vblank_cleanup(struct drm_device *dev); --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -235,7 +235,7 @@ static int drm_getcap(struct drm_device /* Only some caps make sense with UMS/render-only drivers. */ switch (req->capability) { case DRM_CAP_TIMESTAMP_MONOTONIC: - req->value = drm_timestamp_monotonic; + req->value = 1; return 0; case DRM_CAP_PRIME: req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0; --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -82,20 +82,12 @@ drm_get_last_vbltimestamp(struct drm_dev static unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */ -/* - * Default to use monotonic timestamps for wait-for-vblank and page-flip - * complete events. - */ -unsigned int drm_timestamp_monotonic = 1; - static int drm_vblank_offdelay = 5000; /* Default to 5000 msecs. */ 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); MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs] (0: never disable, <0: disable immediately)"); MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]"); -MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps"); static void store_vblank(struct drm_device *dev, unsigned int pipe, u32 vblank_count_inc, @@ -672,9 +664,6 @@ bool drm_calc_vbltimestamp_from_scanoutp delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos), mode->crtc_clock); - if (!drm_timestamp_monotonic) - etime = ktime_mono_to_real(etime); - /* save this only for debugging purposes */ ts_etime = ktime_to_timespec64(etime); ts_vblank_time = ktime_to_timespec64(*vblank_time); @@ -694,11 +683,6 @@ bool drm_calc_vbltimestamp_from_scanoutp } EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos); -static ktime_t get_drm_timestamp(void) -{ - return drm_timestamp_monotonic ? ktime_get() : ktime_get_real(); -} - /** * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent * vblank interval @@ -738,7 +722,7 @@ drm_get_last_vbltimestamp(struct drm_dev * Return current monotonic/gettimeofday timestamp as best estimate. */ if (!ret) - *tvblank = get_drm_timestamp(); + *tvblank = ktime_get(); return ret; } @@ -811,8 +795,8 @@ static void send_vblank_event(struct drm e->event.sequence = seq; /* * e->event is a user space structure, with hardcoded unsigned - * 32-bit seconds/microseconds. This will overflow in 2106 for - * drm_timestamp_monotonic==0, but not with drm_timestamp_monotonic==1 + * 32-bit seconds/microseconds. This is safe as we always use + * monotonic timestamps since linux-4.15 */ e->event.tv_sec = tv.tv_sec; e->event.tv_usec = tv.tv_nsec / 1000; @@ -899,7 +883,7 @@ void drm_crtc_send_vblank_event(struct d } else { seq = 0; - now = get_drm_timestamp(); + now = ktime_get(); } e->pipe = pipe; e->event.crtc_id = crtc->base.id; @@ -1408,9 +1392,8 @@ static void drm_wait_vblank_reply(struct /* * drm_wait_vblank_reply is a UAPI structure that uses 'long' - * to store the seconds. This will overflow in y2038 on 32-bit - * architectures with drm_timestamp_monotonic==0, but not with - * drm_timestamp_monotonic==1 (the default). + * to store the seconds. This is safe as we always use monotonic + * timestamps since linux-4.15. */ reply->sequence = drm_vblank_count_and_time(dev, pipe, &now); ts = ktime_to_timespec64(now);