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@xxxxxxxxx>
---
drivers/media/cec/cec-adap.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c
index d9c6f2c..0ea4efb 100644
--- 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;
--
2.10.2
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