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drm: vblank: remove drm_timestamp_monotonic parameter 

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
c61eef726a ("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 <arnd@arndb.de>
Acked-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Arnd Bergmann 2017-10-11 17:20:13 +02:00 committed by Dave Airlie
parent 67680d3c04
commit 25e1a79874
3 changed files with 7 additions and 25 deletions
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1
drivers/gpu/drm/drm_internal.h
View File

@ -55,7 +55,6 @@ int drm_clients_info(struct seq_file *m, void* data);
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);

2
drivers/gpu/drm/drm_ioctl.c
View File

@ -235,7 +235,7 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
/* 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;

29
drivers/gpu/drm/drm_vblank.c
View File

@ -82,20 +82,12 @@ drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
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_scanoutpos(struct drm_device *dev,
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_scanoutpos(struct drm_device *dev,
}
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_device *dev, unsigned int pipe,
* 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_device *dev,
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 drm_crtc *crtc,
} 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_device *dev, unsigned int pipe,
/*
* 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);