On Fri, May 5, 2017 at 1:35 AM, Bjorn Andersson
[off-list ref] wrote:

+
+static int qcom_apcs_ipc_send_data(struct mbox_chan *chan, void *data)
+{
+       struct qcom_apcs_ipc *apcs = container_of(chan->mbox,
+                                                 struct qcom_apcs_ipc, mbox);
+       unsigned long idx = (unsigned long)chan->con_priv;
+
+       writel(BIT(idx), apcs->base + apcs->offset);
+

When/how does this bit get ever cleared again?
You may want to add last_tx_done() callback to check if this bit is
cleared before you can send the next interrupt. And set
txdone_poll/irq accordingly.

Thanks