drivers/staging/media/ipu3/ipu3-css-pool.c

Source file repositories/reference/linux-study-clean/drivers/staging/media/ipu3/ipu3-css-pool.c

File Facts

System
Linux kernel
Corpus path
drivers/staging/media/ipu3/ipu3-css-pool.c
Extension
.c
Size
2250 bytes
Lines
101
Domain
Driver Families
Bucket
drivers/staging
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 (size == 0) {
			pool->entry[i].param.vaddr = NULL;
			continue;
		}

		if (!imgu_dmamap_alloc(imgu, &pool->entry[i].param, size))
			goto fail;
	}

	pool->last = IPU3_CSS_POOL_SIZE;

	return 0;

fail:
	imgu_css_pool_cleanup(imgu, pool);
	return -ENOMEM;
}

/*
 * Allocate a new parameter via recycling the oldest entry in the pool.
 */
void imgu_css_pool_get(struct imgu_css_pool *pool)
{
	/* Get the oldest entry */
	u32 n = (pool->last + 1) % IPU3_CSS_POOL_SIZE;

	pool->entry[n].valid = true;
	pool->last = n;
}

/*
 * Undo, for all practical purposes, the effect of pool_get().
 */
void imgu_css_pool_put(struct imgu_css_pool *pool)
{
	pool->entry[pool->last].valid = false;
	pool->last = (pool->last + IPU3_CSS_POOL_SIZE - 1) % IPU3_CSS_POOL_SIZE;
}

/**
 * imgu_css_pool_last - Retrieve the nth pool entry from last
 *
 * @pool: a pointer to &struct imgu_css_pool.
 * @n: the distance to the last index.
 *
 * Returns:
 *  The nth entry from last or null map to indicate no frame stored.
 */
const struct imgu_css_map *
imgu_css_pool_last(struct imgu_css_pool *pool, unsigned int n)
{
	static const struct imgu_css_map null_map = { 0 };
	int i = (pool->last + IPU3_CSS_POOL_SIZE - n) % IPU3_CSS_POOL_SIZE;

	WARN_ON(n >= IPU3_CSS_POOL_SIZE);

	if (!pool->entry[i].valid)
		return &null_map;

	return &pool->entry[i].param;
}

Annotation

Implementation Notes