drivers/media/test-drivers/vivid/vivid-kthread-touch.c

Source file repositories/reference/linux-study-clean/drivers/media/test-drivers/vivid/vivid-kthread-touch.c

File Facts

System
Linux kernel
Corpus path
drivers/media/test-drivers/vivid/vivid-kthread-touch.c
Extension
.c
Size
5724 bytes
Lines
197
Domain
Driver Families
Bucket
drivers/media
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

if (!mutex_trylock(&dev->mutex)) {
			schedule();
			continue;
		}
		cur_jiffies = jiffies;
		if (dev->touch_cap_seq_resync) {
			dev->jiffies_touch_cap = cur_jiffies;
			dev->touch_cap_seq_offset = dev->touch_cap_seq_count + 1;
			dev->touch_cap_seq_count = 0;
			dev->cap_seq_resync = false;
		}
		denominator = dev->timeperframe_tch_cap.denominator;
		numerator = dev->timeperframe_tch_cap.numerator;

		/* Calculate the number of jiffies since we started streaming */
		jiffies_since_start = cur_jiffies - dev->jiffies_touch_cap;
		/* Get the number of buffers streamed since the start */
		buffers_since_start = (u64)jiffies_since_start * denominator +
				      (HZ * numerator) / 2;
		do_div(buffers_since_start, HZ * numerator);

		/*
		 * After more than 0xf0000000 (rounded down to a multiple of
		 * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
		 * jiffies have passed since we started streaming reset the
		 * counters and keep track of the sequence offset.
		 */
		if (jiffies_since_start > JIFFIES_RESYNC) {
			dev->jiffies_touch_cap = cur_jiffies;
			dev->cap_seq_offset = buffers_since_start;
			buffers_since_start = 0;
		}
		dropped_bufs = buffers_since_start + dev->touch_cap_seq_offset - dev->touch_cap_seq_count;
		dev->touch_cap_seq_count = buffers_since_start + dev->touch_cap_seq_offset;
		dev->touch_cap_with_seq_wrap_count =
			dev->touch_cap_seq_count - dev->touch_cap_seq_start;

		vivid_thread_tch_cap_tick(dev, dropped_bufs);

		/*
		 * Calculate the number of 'numerators' streamed
		 * since we started, including the current buffer.
		 */
		numerators_since_start = ++buffers_since_start * numerator;

		/* And the number of jiffies since we started */
		jiffies_since_start = jiffies - dev->jiffies_touch_cap;

		mutex_unlock(&dev->mutex);

		/*
		 * Calculate when that next buffer is supposed to start
		 * in jiffies since we started streaming.
		 */
		next_jiffies_since_start = numerators_since_start * HZ +
					   denominator / 2;
		do_div(next_jiffies_since_start, denominator);
		/* If it is in the past, then just schedule asap */
		if (next_jiffies_since_start < jiffies_since_start)
			next_jiffies_since_start = jiffies_since_start;

		wait_jiffies = next_jiffies_since_start - jiffies_since_start;
		if (!time_is_after_jiffies(cur_jiffies + wait_jiffies))
			continue;

		wait_queue_head_t wait;

		init_waitqueue_head(&wait);
		wait_event_interruptible_timeout(wait, kthread_should_stop(),
					cur_jiffies + wait_jiffies - jiffies);
	}
	dprintk(dev, 1, "Touch Capture Thread End\n");
	return 0;
}

int vivid_start_generating_touch_cap(struct vivid_dev *dev)
{
	if (dev->kthread_touch_cap) {
		dev->touch_cap_streaming = true;
		return 0;
	}

	dev->touch_cap_seq_start = dev->seq_wrap * 128;
	dev->kthread_touch_cap = kthread_run(vivid_thread_touch_cap, dev,
					     "%s-tch-cap", dev->v4l2_dev.name);

	if (IS_ERR(dev->kthread_touch_cap)) {
		int err = PTR_ERR(dev->kthread_touch_cap);

		dev->kthread_touch_cap = NULL;

Annotation

Implementation Notes