/*
* Code accessing dma_async_is_complete() in a tight loop
* may give problems - could schedule where indicated.
* If slaves are relying on interrupts to signal completion this
* function must not be called with interrupts disabled
*/
static enum dma_status pl08x_dma_is_complete(struct dma_chan *chan,
dma_cookie_t cookie,
dma_cookie_t *done,
dma_cookie_t *used)
{
struct pl08x_dma_chan *local_chan = container_of(chan,
struct pl08x_dma_chan, chan);
dma_cookie_t last_used;
dma_cookie_t last_complete;
enum dma_status ret;
last_used = atomic_read(&local_chan->last_issued);
last_complete = local_chan->lc;
if (done)
*done = last_complete;
if (used)
*used = last_used;
ret = dma_async_is_complete(cookie, last_complete, last_used);
if (ret == DMA_SUCCESS)
return ret;
/*
* schedule(); could be inserted here
*/
/*
* This cookie not complete yet
*/
last_used = atomic_read(&local_chan->last_issued);
last_complete = local_chan->lc;
if (done)
*done = last_complete;
if (used)
*used = last_used;
return dma_async_is_complete(cookie, last_complete, last_used);
}
|
提供了一个函数,用于检测当前DMA是否已经完成了,实际好像很少用到,多数是用complete机制 |