1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_display_jiffies.h b/drivers/gpu/drm/i915/display/intel_display_jiffies.h
new file mode 100644
index 000000000000..c060c567e262
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_display_jiffies.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright © 2025 Intel Corporation */
+
+#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__ */