[media] cec: ignore messages that we initiated

Some CEC adapters will receive messages that they initiated. Add a
check that will ignore such messages.

Most hardware behaves correctly in this respect, but I have seen
adapters that don't, so just filter this out in the framework.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
index d9c6f2c1c6fa6404ec1a65627a9637ee6105c3c5..0ea4efb3de6683ee2dca71b3b7e20bc7f5f1e761 100644 (file)
--- a/drivers/media/cec/cec-adap.c
+++ b/drivers/media/cec/cec-adap.c
@@ -869,6 +869,21 @@ void cec_received_msg(struct cec_adapter *adap, struct cec_msg *msg)
        if (WARN_ON(!msg->len || msg->len > CEC_MAX_MSG_SIZE))
                return;
 
+       /*
+        * Some CEC adapters will receive the messages that they transmitted.
+        * This test filters out those messages by checking if we are the
+        * initiator, and just returning in that case.
+        *
+        * Note that this won't work if this is an Unregistered device.
+        *
+        * It is bad practice if the hardware receives the message that it
+        * transmitted and luckily most CEC adapters behave correctly in this
+        * respect.
+        */
+       if (msg_init != CEC_LOG_ADDR_UNREGISTERED &&
+           cec_has_log_addr(adap, msg_init))
+               return;
+
        msg->rx_ts = ktime_get_ns();
        msg->rx_status = CEC_RX_STATUS_OK;
        msg->sequence = msg->reply = msg->timeout = 0;