Commit de7e8bd0 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Daniel Vetter
Browse files

drm: via: use ktime_get() instead of do_gettimeofday 



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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171104212131.2939989-1-arnd@arndb.de
parent 0338f0d0

drivers/gpu/drm/via/via_drv.h

+2 −2
Original line number Diff line number Diff line
@@ -74,9 +74,9 @@ typedef struct drm_via_private { 
	volatile uint32_t *last_pause_ptr;

	volatile uint32_t *hw_addr_ptr;

	drm_via_ring_buffer_t ring;

	struct timeval last_vblank;

	ktime_t last_vblank;

	int last_vblank_valid;

	unsigned usec_per_vblank;

	ktime_t nsec_per_vblank;

	atomic_t vbl_received;

	drm_via_state_t hc_state;

	char pci_buf[VIA_PCI_BUF_SIZE];

drivers/gpu/drm/via/via_irq.c

+7 −14
Original line number Diff line number Diff line
@@ -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;

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