From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
If a receive is in progress or starts before the transmit has
a chance, then lower the Signal Free Time of the upcoming transmit
to no more than CEC_SIGNAL_FREE_TIME_NEW_INITIATOR.
This is per the specification requirements.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
drivers/media/cec/cec-pin.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/media/cec/cec-pin.c b/drivers/media/cec/cec-pin.c
index 6e311424f0dc..635db8e70ead 100644
--- a/drivers/media/cec/cec-pin.c
+++ b/drivers/media/cec/cec-pin.c
@@ -935,6 +935,17 @@ static enum hrtimer_restart cec_pin_timer(struct hrtimer *timer)
/* Start bit, switch to receive state */
pin->ts = ts;
pin->state = CEC_ST_RX_START_BIT_LOW;
+ /*
+ * If a transmit is pending, then that transmit should
+ * use a signal free time of no more than
+ * CEC_SIGNAL_FREE_TIME_NEW_INITIATOR since it will
+ * have a new initiator due to the receive that is now
+ * starting.
+ */
+ if (pin->tx_msg.len && pin->tx_signal_free_time >
+ CEC_SIGNAL_FREE_TIME_NEW_INITIATOR)
+ pin->tx_signal_free_time =
+ CEC_SIGNAL_FREE_TIME_NEW_INITIATOR;
break;
}
if (ktime_to_ns(pin->ts) == 0)
@@ -1157,6 +1168,15 @@ static int cec_pin_adap_transmit(struct cec_adapter *adap, u8 attempts,
{
struct cec_pin *pin = adap->pin;
+ /*
+ * If a receive is in progress, then this transmit should use
+ * a signal free time of max CEC_SIGNAL_FREE_TIME_NEW_INITIATOR
+ * since when it starts transmitting it will have a new initiator.
+ */
+ if (pin->state != CEC_ST_IDLE &&
+ signal_free_time > CEC_SIGNAL_FREE_TIME_NEW_INITIATOR)
+ signal_free_time = CEC_SIGNAL_FREE_TIME_NEW_INITIATOR;
+
pin->tx_signal_free_time = signal_free_time;
pin->tx_extra_bytes = 0;
pin->tx_msg = *msg;
--
2.18.0
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