drivers/gpu/drm/i915/display/intel_display_jiffies.h

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/i915/display/intel_display_jiffies.h

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/i915/display/intel_display_jiffies.h
Extension
.h
Size
1317 bytes
Lines
44
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __INTEL_DISPLAY_JIFFIES_H__
#define __INTEL_DISPLAY_JIFFIES_H__

#include <linux/jiffies.h>

static inline unsigned long msecs_to_jiffies_timeout(const unsigned int m)
{
	unsigned long j = msecs_to_jiffies(m);

	return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);
}

/*
 * If you need to wait X milliseconds between events A and B, but event B
 * doesn't happen exactly after event A, you record the timestamp (jiffies) of
 * when event A happened, then just before event B you call this function and
 * pass the timestamp as the first argument, and X as the second argument.
 */
static inline void
wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
{
	unsigned long target_jiffies, tmp_jiffies, remaining_jiffies;

	/*
	 * Don't re-read the value of "jiffies" every time since it may change
	 * behind our back and break the math.
	 */
	tmp_jiffies = jiffies;
	target_jiffies = timestamp_jiffies +
			 msecs_to_jiffies_timeout(to_wait_ms);

	if (time_after(target_jiffies, tmp_jiffies)) {
		remaining_jiffies = target_jiffies - tmp_jiffies;
		while (remaining_jiffies)
			remaining_jiffies =
			    schedule_timeout_uninterruptible(remaining_jiffies);
	}
}

#endif /* __INTEL_DISPLAY_JIFFIES_H__ */

Annotation

Implementation Notes