From: Hans Verkuil hans.verkuil@cisco.com
[ Upstream commit c439d5c1e13dbf66cff53455432f21d4d0536c51 ]
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@cisco.com Signed-off-by: Mauro Carvalho Chehab mchehab+samsung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c003b8eac6176..68fc6a24d0771 100644 --- a/drivers/media/cec/cec-pin.c +++ b/drivers/media/cec/cec-pin.c @@ -529,6 +529,17 @@ 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 (pin->ts == 0) @@ -690,6 +701,15 @@ 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_msg = *msg; pin->work_tx_status = 0;