iter = tx;
/* find the root of the unsubmitted dependency chain */
- while (iter->cookie == -EBUSY) {
+ do {
parent = iter->parent;
- if (parent && parent->cookie == -EBUSY)
- iter = iter->parent;
- else
+ if (!parent)
break;
- }
+ else
+ iter = parent;
+ } while (parent);
+
+ /* there is a small window for ->parent == NULL and
+ * ->cookie == -EBUSY
+ */
+ while (iter->cookie == -EBUSY)
+ cpu_relax();
status = dma_sync_wait(iter->chan, iter->cookie);
} while (status == DMA_IN_PROGRESS || (iter != tx));
void
async_tx_run_dependencies(struct dma_async_tx_descriptor *tx)
{
- struct dma_async_tx_descriptor *dep_tx, *_dep_tx;
- struct dma_device *dev;
+ struct dma_async_tx_descriptor *next = tx->next;
struct dma_chan *chan;
- list_for_each_entry_safe(dep_tx, _dep_tx, &tx->depend_list,
- depend_node) {
- chan = dep_tx->chan;
- dev = chan->device;
- /* we can't depend on ourselves */
- BUG_ON(chan == tx->chan);
- list_del(&dep_tx->depend_node);
- tx->tx_submit(dep_tx);
-
- /* we need to poke the engine as client code does not
- * know about dependency submission events
- */
- dev->device_issue_pending(chan);
+ if (!next)
+ return;
+
+ tx->next = NULL;
+ chan = next->chan;
+
+ /* keep submitting up until a channel switch is detected
+ * in that case we will be called again as a result of
+ * processing the interrupt from async_tx_channel_switch
+ */
+ while (next && next->chan == chan) {
+ struct dma_async_tx_descriptor *_next;
+
+ spin_lock_bh(&next->lock);
+ next->parent = NULL;
+ _next = next->next;
+ next->next = NULL;
+ spin_unlock_bh(&next->lock);
+
+ next->tx_submit(next);
+ next = _next;
}
+
+ chan->device->device_issue_pending(chan);
}
EXPORT_SYMBOL_GPL(async_tx_run_dependencies);
}
#endif
+
+/**
+ * async_tx_channel_switch - queue an interrupt descriptor with a dependency
+ * pre-attached.
+ * @depend_tx: the operation that must finish before the new operation runs
+ * @tx: the new operation
+ */
+static void
+async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
+ struct dma_async_tx_descriptor *tx)
+{
+ struct dma_chan *chan;
+ struct dma_device *device;
+ struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
+
+ /* first check to see if we can still append to depend_tx */
+ spin_lock_bh(&depend_tx->lock);
+ if (depend_tx->parent && depend_tx->chan == tx->chan) {
+ tx->parent = depend_tx;
+ depend_tx->next = tx;
+ intr_tx = NULL;
+ }
+ spin_unlock_bh(&depend_tx->lock);
+
+ if (!intr_tx)
+ return;
+
+ chan = depend_tx->chan;
+ device = chan->device;
+
+ /* see if we can schedule an interrupt
+ * otherwise poll for completion
+ */
+ if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
+ intr_tx = device->device_prep_dma_interrupt(chan);
+ else
+ intr_tx = NULL;
+
+ if (intr_tx) {
+ intr_tx->callback = NULL;
+ intr_tx->callback_param = NULL;
+ tx->parent = intr_tx;
+ /* safe to set ->next outside the lock since we know we are
+ * not submitted yet
+ */
+ intr_tx->next = tx;
+
+ /* check if we need to append */
+ spin_lock_bh(&depend_tx->lock);
+ if (depend_tx->parent) {
+ intr_tx->parent = depend_tx;
+ depend_tx->next = intr_tx;
+ async_tx_ack(intr_tx);
+ intr_tx = NULL;
+ }
+ spin_unlock_bh(&depend_tx->lock);
+
+ if (intr_tx) {
+ intr_tx->parent = NULL;
+ intr_tx->tx_submit(intr_tx);
+ async_tx_ack(intr_tx);
+ }
+ } else {
+ if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
+ panic("%s: DMA_ERROR waiting for depend_tx\n",
+ __func__);
+ tx->tx_submit(tx);
+ }
+}
+
+
+/**
+ * submit_disposition - while holding depend_tx->lock we must avoid submitting
+ * new operations to prevent a circular locking dependency with
+ * drivers that already hold a channel lock when calling
+ * async_tx_run_dependencies.
+ * @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
+ * @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
+ * @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
+ */
+enum submit_disposition {
+ ASYNC_TX_SUBMITTED,
+ ASYNC_TX_CHANNEL_SWITCH,
+ ASYNC_TX_DIRECT_SUBMIT,
+};
+
void
async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
tx->callback = cb_fn;
tx->callback_param = cb_param;
- /* set this new tx to run after depend_tx if:
- * 1/ a dependency exists (depend_tx is !NULL)
- * 2/ the tx can not be submitted to the current channel
- */
- if (depend_tx && depend_tx->chan != chan) {
- /* if ack is already set then we cannot be sure
+ if (depend_tx) {
+ enum submit_disposition s;
+
+ /* sanity check the dependency chain:
+ * 1/ if ack is already set then we cannot be sure
* we are referring to the correct operation
+ * 2/ dependencies are 1:1 i.e. two transactions can
+ * not depend on the same parent
*/
- BUG_ON(depend_tx->ack);
+ BUG_ON(depend_tx->ack || depend_tx->next || tx->parent);
- tx->parent = depend_tx;
+ /* the lock prevents async_tx_run_dependencies from missing
+ * the setting of ->next when ->parent != NULL
+ */
spin_lock_bh(&depend_tx->lock);
- list_add_tail(&tx->depend_node, &depend_tx->depend_list);
- if (depend_tx->cookie == 0) {
- struct dma_chan *dep_chan = depend_tx->chan;
- struct dma_device *dep_dev = dep_chan->device;
- dep_dev->device_dependency_added(dep_chan);
+ if (depend_tx->parent) {
+ /* we have a parent so we can not submit directly
+ * if we are staying on the same channel: append
+ * else: channel switch
+ */
+ if (depend_tx->chan == chan) {
+ tx->parent = depend_tx;
+ depend_tx->next = tx;
+ s = ASYNC_TX_SUBMITTED;
+ } else
+ s = ASYNC_TX_CHANNEL_SWITCH;
+ } else {
+ /* we do not have a parent so we may be able to submit
+ * directly if we are staying on the same channel
+ */
+ if (depend_tx->chan == chan)
+ s = ASYNC_TX_DIRECT_SUBMIT;
+ else
+ s = ASYNC_TX_CHANNEL_SWITCH;
}
spin_unlock_bh(&depend_tx->lock);
- /* schedule an interrupt to trigger the channel switch */
- async_trigger_callback(ASYNC_TX_ACK, depend_tx, NULL, NULL);
+ switch (s) {
+ case ASYNC_TX_SUBMITTED:
+ break;
+ case ASYNC_TX_CHANNEL_SWITCH:
+ async_tx_channel_switch(depend_tx, tx);
+ break;
+ case ASYNC_TX_DIRECT_SUBMIT:
+ tx->parent = NULL;
+ tx->tx_submit(tx);
+ break;
+ }
} else {
tx->parent = NULL;
tx->tx_submit(tx);
git.openpandora.org / pandora-kernel.git / commitdiff