drivers/gpu/host1x/fence.c

Source file repositories/reference/linux-study-clean/drivers/gpu/host1x/fence.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/host1x/fence.c
Extension
.c
Size
3901 bytes
Lines
155
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Syncpoint dma_fence implementation
 *
 * Copyright (c) 2020, NVIDIA Corporation.
 */

#include <linux/dma-fence.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/sync_file.h>

#include "fence.h"
#include "intr.h"
#include "syncpt.h"

static const char *host1x_syncpt_fence_get_driver_name(struct dma_fence *f)
{
	return "host1x";
}

static const char *host1x_syncpt_fence_get_timeline_name(struct dma_fence *f)
{
	return "syncpoint";
}

static struct host1x_syncpt_fence *to_host1x_fence(struct dma_fence *f)
{
	return container_of(f, struct host1x_syncpt_fence, base);
}

static bool host1x_syncpt_fence_enable_signaling(struct dma_fence *f)
{
	struct host1x_syncpt_fence *sf = to_host1x_fence(f);

	if (host1x_syncpt_is_expired(sf->sp, sf->threshold))
		return false;

	/* Reference for interrupt path. */
	dma_fence_get(f);

	/*
	 * The dma_fence framework requires the fence driver to keep a
	 * reference to any fences for which 'enable_signaling' has been
	 * called (and that have not been signalled).
	 *
	 * We cannot currently always guarantee that all fences get signalled
	 * or cancelled. As such, for such situations, set up a timeout, so
	 * that long-lasting fences will get reaped eventually.
	 */
	if (sf->timeout) {
		/* Reference for timeout path. */
		dma_fence_get(f);
		schedule_delayed_work(&sf->timeout_work, msecs_to_jiffies(30000));
	}

	host1x_intr_add_fence_locked(sf->sp->host, sf);

	/*
	 * The fence may get signalled at any time after the above call,
	 * so we need to initialize all state used by signalling
	 * before it.
	 */

	return true;
}

static const struct dma_fence_ops host1x_syncpt_fence_ops = {
	.get_driver_name = host1x_syncpt_fence_get_driver_name,
	.get_timeline_name = host1x_syncpt_fence_get_timeline_name,
	.enable_signaling = host1x_syncpt_fence_enable_signaling,
};

void host1x_fence_signal(struct host1x_syncpt_fence *f)
{
	if (atomic_xchg(&f->signaling, 1)) {
		/*
		 * Already on timeout path, but we removed the fence before
		 * timeout path could, so drop interrupt path reference.
		 */
		dma_fence_put(&f->base);
		return;
	}

	if (f->timeout && cancel_delayed_work(&f->timeout_work)) {
		/*
		 * We know that the timeout path will not be entered.
		 * Safe to drop the timeout path's reference now.
		 */

Annotation

Implementation Notes