[PATCH 13/18] rpmsg: glink: Add rx done command

On 8/22/2017 7:46 PM, Sricharan R wrote:

Hi,

quoted

quoted

+??? /* Take it off the tree of receive intents */
+??? if (!intent->reuse) {
+??????? spin_lock(&channel->intent_lock);
+??????? idr_remove(&channel->liids, intent->id);
+??????? spin_unlock(&channel->intent_lock);
+??? }
+
+??? /* Schedule the sending of a rx_done indication */
+??? spin_lock(&channel->intent_lock);
+??? list_add_tail(&intent->node, &channel->done_intents);
+??? spin_unlock(&channel->intent_lock);
+
+??? schedule_work(&channel->intent_work);

Adding one more parallel path will hit performance, if this worker could not get CPU cycles
or blocked by other RT or HIGH_PRIO worker on global worker pool.

  The idea is, by design to have parallel non-blocking paths for rx and tx (that is done as a
  part of rx by sending the rx_done command), otherwise trying to send the rx_done
  command in the rx isr context is a problem since the tx can wait for the FIFO space and
  in worst case, can even lead to a potential deadlock if both the local and remote try
  the same. Having said that, instead of queuing this work in to the global queue, this
  can be put in to a local glink edge owned queue (or) a threaded isr ?, downstream does the
  rx_done in a client specific worker.

Yes, mixing RX and TX path will cause dead lock. I am okay to use 
specific queue with HIGH_PRIO or a threaded isr.
down stream uses both client specific worker and client RX cb [this mix 
the TX and RX path] which want to avoid.

Regards,
  Sricharan