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drm: via: use ktime_get() instead of do_gettimeofday

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We want to remove uses of do_gettimeofday() from the kernel since the
resulting timeval structure overflows in 2038. This is not a problem for
this particular use, but do_gettimeofday() is also not an appropriate
method for measuring time intervals, since it requires a conversion into
microseconds and is complicated to work with.

ktime_get() is a better replacement, as it works with the monontonic
kernel timebase and requires a minimum of computation.

I'm slightly changing the output from microseconds to nanoseconds here,
to avoid introducing a new division operation. This should be fine
since the value is only used for debugging.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171104212131.2939989-1-arnd@arndb.de
This commit is contained in:
Arnd Bergmann
2017-11-04 22:20:08 +01:00
committed by Daniel Vetter
parent 0338f0d0d7
commit de7e8bd01a
2 changed files with 9 additions and 16 deletions
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21
drivers/gpu/drm/via/via_irq.c
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@@ -88,13 +88,6 @@ static int via_num_unichrome = ARRAY_SIZE(via_unichrome_irqs);
static int via_irqmap_unichrome[] = {-1, -1, -1, 0, -1, 1};
static unsigned time_diff(struct timeval *now, struct timeval *then)
{
return (now->tv_usec >= then->tv_usec) ?
now->tv_usec - then->tv_usec :
1000000 - (then->tv_usec - now->tv_usec);
}
u32 via_get_vblank_counter(struct drm_device *dev, unsigned int pipe)
{
drm_via_private_t *dev_priv = dev->dev_private;
@@ -111,7 +104,7 @@ irqreturn_t via_driver_irq_handler(int irq, void *arg)
drm_via_private_t *dev_priv = (drm_via_private_t *) dev->dev_private;
u32 status;
int handled = 0;
struct timeval cur_vblank;
ktime_t cur_vblank;
drm_via_irq_t *cur_irq = dev_priv->via_irqs;
int i;
@@ -119,18 +112,18 @@ irqreturn_t via_driver_irq_handler(int irq, void *arg)
if (status & VIA_IRQ_VBLANK_PENDING) {
atomic_inc(&dev_priv->vbl_received);
if (!(atomic_read(&dev_priv->vbl_received) & 0x0F)) {
do_gettimeofday(&cur_vblank);
cur_vblank = ktime_get();
if (dev_priv->last_vblank_valid) {
dev_priv->usec_per_vblank =
time_diff(&cur_vblank,
&dev_priv->last_vblank) >> 4;
dev_priv->nsec_per_vblank =
ktime_sub(cur_vblank,
dev_priv->last_vblank) >> 4;
}
dev_priv->last_vblank = cur_vblank;
dev_priv->last_vblank_valid = 1;
}
if (!(atomic_read(&dev_priv->vbl_received) & 0xFF)) {
DRM_DEBUG("US per vblank is: %u\n",
dev_priv->usec_per_vblank);
DRM_DEBUG("nsec per vblank is: %llu\n",
ktime_to_ns(dev_priv->nsec_per_vblank));
}
drm_handle_vblank(dev, 0);
handled = 1;