On Sat, May 6, 2017 at 6:49 AM, Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> wrote: > On Fri 05 May 13:22 PDT 2017, Jassi Brar wrote: >> How is it supposed to work if a client queues more than one request? > > One such example is found in patch 5 in this series. There are two FIFOs > in shared memory, one in each direction. Each fifo has a index-pair > associated; a write-index is used by the writer to inform the reader > where the valid data in the ring buffer ends and a read-index indicates > to the writer how far behind the read is. > > The writer will just push data into the FIFO, each time firing off an > APCS IPC interrupt and when the remote interrupt handler runs it will > consume all the messages from the read-index to the write-index. All > without the need for the reader to signal the writer that it has > received the interrupts. > > In the event that the write-index catches up with the read-index a > dedicated flag is set which will cause the reader to signal that the > read-index is updated - allowing the writer to sleep waiting for room in > the FIFO. > Interesting.Just for my enlightenment... Where does the writer sleep in the driver? I see it simply sets the bit and leave. Such a flag (or head and tail pointers matching) should be checked in last_tx_done() If you think RPM will _always_ be ready to accept new messages (though we have seen that doesn't hold in some situations), then you don't need last_tx_done. The client should call mbox_client_txdone() after mbox_send_message(). thnx -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
