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Commit 35c8125c authored by Hans Verkuil's avatar Hans Verkuil Committed by Greg Kroah-Hartman
Browse files

media: cec-gpio: select correct Signal Free Time 



[ 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: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 58d0a3db

drivers/media/cec/cec-pin.c

+20 −0
Original line number Diff line number Diff line
@@ -936,6 +936,17 @@ 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)
@@ -1158,6 +1169,15 @@ 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;