| Message ID | 20171102114415.1811842-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | exynos: drm: use monotonic timestamps | expand |
Hello Arnd, I guess you could coordinate the IPP changes with Marek, who is rewriting the IPP subsystem anyway (added Marek to Cc). Here is the most recent IPPv2 series: https://www.spinics.net/lists/linux-samsung-soc/msg61066.html Concerning the G2D changes, I don't think anything in userspace uses the timestamps (e.g. for synchronisation). With best wishes, Tobias Arnd Bergmann wrote: > The exynos DRM driver uses real-time 'struct timeval' values > for exporting its timestamps to user space. This has multiple > problems: > > 1. signed seconds overflow in y2038 > 2. the 'struct timeval' definition is deprecated in the kernel > 3. time may jump or go backwards after a 'settimeofday()' syscall > 4. other DRM timestamps are in CLOCK_MONOTONIC domain, so they > can't be compared > 5. exporting microseconds requires a division by 1000, which may > be slow on some architectures. > > Ideally timestamps should just use 64-bit nanoseconds instead, but > of course we can't change that now. Instead, this tries to address > the first four points above by using monotonic 'timespec' values. > > The downside is that there is a small risk of breaking user space > if that expects the absolute timestamp numbers to relate to the > result of 'gettimeofday()'. Please review the user space driver > before applying this patch to ensure this works. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpu/drm/exynos/exynos_drm_g2d.c | 6 +++--- > drivers/gpu/drm/exynos/exynos_drm_ipp.c | 8 ++++---- > 2 files changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c > index 2b8bf2dd6387..9effe40f5fa5 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c > @@ -926,7 +926,7 @@ static void g2d_finish_event(struct g2d_data *g2d, u32 cmdlist_no) > struct drm_device *drm_dev = g2d->subdrv.drm_dev; > struct g2d_runqueue_node *runqueue_node = g2d->runqueue_node; > struct drm_exynos_pending_g2d_event *e; > - struct timeval now; > + struct timespec64 now; > > if (list_empty(&runqueue_node->event_list)) > return; > @@ -934,9 +934,9 @@ static void g2d_finish_event(struct g2d_data *g2d, u32 cmdlist_no) > e = list_first_entry(&runqueue_node->event_list, > struct drm_exynos_pending_g2d_event, base.link); > > - do_gettimeofday(&now); > + ktime_get_ts64(&now); > e->event.tv_sec = now.tv_sec; > - e->event.tv_usec = now.tv_usec; > + e->event.tv_usec = now.tv_nsec / NSEC_PER_USEC; > e->event.cmdlist_no = cmdlist_no; > > drm_send_event(drm_dev, &e->base); > diff --git a/drivers/gpu/drm/exynos/exynos_drm_ipp.c b/drivers/gpu/drm/exynos/exynos_drm_ipp.c > index 3edda18cc2d2..3f9d8d79bbde 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_ipp.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_ipp.c > @@ -1406,7 +1406,7 @@ static int ipp_send_event(struct exynos_drm_ippdrv *ippdrv, > struct drm_exynos_ipp_queue_buf qbuf; > struct drm_exynos_ipp_send_event *e; > struct list_head *head; > - struct timeval now; > + struct timespec64 now; > u32 tbuf_id[EXYNOS_DRM_OPS_MAX] = {0, }; > int ret, i; > > @@ -1509,10 +1509,10 @@ static int ipp_send_event(struct exynos_drm_ippdrv *ippdrv, > e = list_first_entry(&c_node->event_list, > struct drm_exynos_ipp_send_event, base.link); > > - do_gettimeofday(&now); > - DRM_DEBUG_KMS("tv_sec[%ld]tv_usec[%ld]\n", now.tv_sec, now.tv_usec); > + ktime_get_ts64(&now); > + DRM_DEBUG_KMS("tv_sec[%lld]tv_nsec[%ld]\n", (s64)now.tv_sec, now.tv_nsec); > e->event.tv_sec = now.tv_sec; > - e->event.tv_usec = now.tv_usec; > + e->event.tv_usec = now.tv_nsec / NSEC_PER_USEC; > e->event.prop_id = property->prop_id; > > /* set buffer id about source destination */ >
diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c index 2b8bf2dd6387..9effe40f5fa5 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c @@ -926,7 +926,7 @@ static void g2d_finish_event(struct g2d_data *g2d, u32 cmdlist_no) struct drm_device *drm_dev = g2d->subdrv.drm_dev; struct g2d_runqueue_node *runqueue_node = g2d->runqueue_node; struct drm_exynos_pending_g2d_event *e; - struct timeval now; + struct timespec64 now; if (list_empty(&runqueue_node->event_list)) return; @@ -934,9 +934,9 @@ static void g2d_finish_event(struct g2d_data *g2d, u32 cmdlist_no) e = list_first_entry(&runqueue_node->event_list, struct drm_exynos_pending_g2d_event, base.link); - do_gettimeofday(&now); + ktime_get_ts64(&now); e->event.tv_sec = now.tv_sec; - e->event.tv_usec = now.tv_usec; + e->event.tv_usec = now.tv_nsec / NSEC_PER_USEC; e->event.cmdlist_no = cmdlist_no; drm_send_event(drm_dev, &e->base); diff --git a/drivers/gpu/drm/exynos/exynos_drm_ipp.c b/drivers/gpu/drm/exynos/exynos_drm_ipp.c index 3edda18cc2d2..3f9d8d79bbde 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_ipp.c +++ b/drivers/gpu/drm/exynos/exynos_drm_ipp.c @@ -1406,7 +1406,7 @@ static int ipp_send_event(struct exynos_drm_ippdrv *ippdrv, struct drm_exynos_ipp_queue_buf qbuf; struct drm_exynos_ipp_send_event *e; struct list_head *head; - struct timeval now; + struct timespec64 now; u32 tbuf_id[EXYNOS_DRM_OPS_MAX] = {0, }; int ret, i; @@ -1509,10 +1509,10 @@ static int ipp_send_event(struct exynos_drm_ippdrv *ippdrv, e = list_first_entry(&c_node->event_list, struct drm_exynos_ipp_send_event, base.link); - do_gettimeofday(&now); - DRM_DEBUG_KMS("tv_sec[%ld]tv_usec[%ld]\n", now.tv_sec, now.tv_usec); + ktime_get_ts64(&now); + DRM_DEBUG_KMS("tv_sec[%lld]tv_nsec[%ld]\n", (s64)now.tv_sec, now.tv_nsec); e->event.tv_sec = now.tv_sec; - e->event.tv_usec = now.tv_usec; + e->event.tv_usec = now.tv_nsec / NSEC_PER_USEC; e->event.prop_id = property->prop_id; /* set buffer id about source destination */
The exynos DRM driver uses real-time 'struct timeval' values for exporting its timestamps to user space. This has multiple problems: 1. signed seconds overflow in y2038 2. the 'struct timeval' definition is deprecated in the kernel 3. time may jump or go backwards after a 'settimeofday()' syscall 4. other DRM timestamps are in CLOCK_MONOTONIC domain, so they can't be compared 5. exporting microseconds requires a division by 1000, which may be slow on some architectures. Ideally timestamps should just use 64-bit nanoseconds instead, but of course we can't change that now. Instead, this tries to address the first four points above by using monotonic 'timespec' values. The downside is that there is a small risk of breaking user space if that expects the absolute timestamp numbers to relate to the result of 'gettimeofday()'. Please review the user space driver before applying this patch to ensure this works. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 6 +++--- drivers/gpu/drm/exynos/exynos_drm_ipp.c | 8 ++++---- 2 files changed, 7 insertions(+), 7 deletions(-)