diff options
| author |   Hans Verkuil <hans.verkuil@cisco.com> | 2018-10-05 08:51:45 -0400 |
|---|---|---|
| committer |   Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-10-05 11:27:46 -0400 |
| commit | c439d5c1e13dbf66cff53455432f21d4d0536c51 (patch) | |
| tree | 7d71b18d4d8a7fec652a2de6c0ab9e01aab877e4 /drivers/media | |
| parent | media: cec: fix the Signal Free Time calculation (diff) | |
| download | linux-dev-c439d5c1e13dbf66cff53455432f21d4d0536c51.tar.xz linux-dev-c439d5c1e13dbf66cff53455432f21d4d0536c51.zip | |
media: cec-gpio: select correct Signal Free Time
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>
Diffstat (limited to 'drivers/media')
| -rw-r--r-- | drivers/media/cec/cec-pin.c | 20 |
1 files changed, 20 insertions, 0 deletions
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; |