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media: cec: improve CEC pin event handling 

It turns out that the struct cec_fh event buffer size of 64 events
(64 for CEC_EVENT_PIN_CEC_LOW and 64 for _HIGH) is too small. It's
about 160 ms worth of events and if the Raspberry Pi is busy, then it
might take too long for the application to be scheduled so that it can
drain the pending events. Increase these buffers to 800 events which
is at least 2 seconds worth of events.

There is also a FIFO in between the interrupt and the cec-pin thread.
The thread passes the events on to the CEC core. It is important that
should this FIFO fill up the cec core will be informed that events
have been lost so this can be communicated to the user by setting
CEC_EVENT_FL_DROPPED_EVENTS.

It is very hard to debug CEC problems if events were lost without
informing the user of that fact.

If events were dropped due to the FIFO filling up, then the debugfs
status file will let you know how many events were dropped.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Hans Verkuil 2018-03-06 16:20:00 -05:00 committed by Mauro Carvalho Chehab
parent 2b76e5392d
commit 6ec1cbf6b1
5 changed files with 43 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/media/cec/cec-adap.c
View File

@ -73,8 +73,8 @@ static unsigned int cec_log_addr2dev(const struct cec_adapter *adap, u8 log_addr
void cec_queue_event_fh(struct cec_fh *fh,
const struct cec_event *new_ev, u64 ts)
{
static const u8 max_events[CEC_NUM_EVENTS] = {
1, 1, 64, 64, 8, 8,
static const u16 max_events[CEC_NUM_EVENTS] = {
1, 1, 800, 800, 8, 8,
};
struct cec_event_entry *entry;
unsigned int ev_idx = new_ev->event - 1;
@ -142,11 +142,13 @@ static void cec_queue_event(struct cec_adapter *adap,
}
/* Notify userspace that the CEC pin changed state at the given time. */
void cec_queue_pin_cec_event(struct cec_adapter *adap, bool is_high, ktime_t ts)
void cec_queue_pin_cec_event(struct cec_adapter *adap, bool is_high,
bool dropped_events, ktime_t ts)
{
struct cec_event ev = {
.event = is_high ? CEC_EVENT_PIN_CEC_HIGH :
CEC_EVENT_PIN_CEC_LOW,
.flags = dropped_events ? CEC_EVENT_FL_DROPPED_EVENTS : 0,
};
struct cec_fh *fh;

10
drivers/media/cec/cec-pin-priv.h
View File

@ -153,7 +153,9 @@ enum cec_pin_state {
/* The default for the low/high time of the custom pulse */
#define CEC_TIM_CUSTOM_DEFAULT 1000
#define CEC_NUM_PIN_EVENTS 128
#define CEC_NUM_PIN_EVENTS 128
#define CEC_PIN_EVENT_FL_IS_HIGH (1 << 0)
#define CEC_PIN_EVENT_FL_DROPPED (1 << 1)
#define CEC_PIN_IRQ_UNCHANGED 0
#define CEC_PIN_IRQ_DISABLE 1
@ -198,11 +200,13 @@ struct cec_pin {
u8 work_tx_status;
ktime_t work_tx_ts;
atomic_t work_irq_change;
atomic_t work_pin_events;
atomic_t work_pin_num_events;
unsigned int work_pin_events_wr;
unsigned int work_pin_events_rd;
ktime_t work_pin_ts[CEC_NUM_PIN_EVENTS];
bool work_pin_is_high[CEC_NUM_PIN_EVENTS];
u8 work_pin_events[CEC_NUM_PIN_EVENTS];
bool work_pin_events_dropped;
u32 work_pin_events_dropped_cnt;
ktime_t timer_ts;
u32 timer_cnt;
u32 timer_100ms_overruns;

31
drivers/media/cec/cec-pin.c
View File

@ -114,12 +114,21 @@ static void cec_pin_update(struct cec_pin *pin, bool v, bool force)
return;
pin->adap->cec_pin_is_high = v;
if (atomic_read(&pin->work_pin_events) < CEC_NUM_PIN_EVENTS) {
pin->work_pin_is_high[pin->work_pin_events_wr] = v;
if (atomic_read(&pin->work_pin_num_events) < CEC_NUM_PIN_EVENTS) {
u8 ev = v;
if (pin->work_pin_events_dropped) {
pin->work_pin_events_dropped = false;
v |= CEC_PIN_EVENT_FL_DROPPED;
}
pin->work_pin_events[pin->work_pin_events_wr] = ev;
pin->work_pin_ts[pin->work_pin_events_wr] = ktime_get();
pin->work_pin_events_wr =
(pin->work_pin_events_wr + 1) % CEC_NUM_PIN_EVENTS;
atomic_inc(&pin->work_pin_events);
atomic_inc(&pin->work_pin_num_events);
} else {
pin->work_pin_events_dropped = true;
pin->work_pin_events_dropped_cnt++;
}
wake_up_interruptible(&pin->kthread_waitq);
}
@ -1019,7 +1028,7 @@ static int cec_pin_thread_func(void *_adap)
pin->work_rx_msg.len ||
pin->work_tx_status ||
atomic_read(&pin->work_irq_change) ||
atomic_read(&pin->work_pin_events));
atomic_read(&pin->work_pin_num_events));
if (pin->work_rx_msg.len) {
struct cec_msg *msg = &pin->work_rx_msg;
@ -1047,14 +1056,16 @@ static int cec_pin_thread_func(void *_adap)
pin->work_tx_ts);
}
while (atomic_read(&pin->work_pin_events)) {
while (atomic_read(&pin->work_pin_num_events)) {
unsigned int idx = pin->work_pin_events_rd;
u8 v = pin->work_pin_events[idx];
cec_queue_pin_cec_event(adap,
pin->work_pin_is_high[idx],
v & CEC_PIN_EVENT_FL_IS_HIGH,
v & CEC_PIN_EVENT_FL_DROPPED,
pin->work_pin_ts[idx]);
pin->work_pin_events_rd = (idx + 1) % CEC_NUM_PIN_EVENTS;
atomic_dec(&pin->work_pin_events);
atomic_dec(&pin->work_pin_num_events);
}
switch (atomic_xchg(&pin->work_irq_change,
@ -1090,8 +1101,9 @@ static int cec_pin_adap_enable(struct cec_adapter *adap, bool enable)
pin->enabled = enable;
if (enable) {
atomic_set(&pin->work_pin_events, 0);
atomic_set(&pin->work_pin_num_events, 0);
pin->work_pin_events_rd = pin->work_pin_events_wr = 0;
pin->work_pin_events_dropped = false;
cec_pin_read(pin);
cec_pin_to_idle(pin);
pin->tx_msg.len = 0;
@ -1171,6 +1183,8 @@ static void cec_pin_adap_status(struct cec_adapter *adap,
seq_printf(file, "tx_bit: %d\n", pin->tx_bit);
seq_printf(file, "rx_bit: %d\n", pin->rx_bit);
seq_printf(file, "cec pin: %d\n", pin->ops->read(adap));
seq_printf(file, "cec pin events dropped: %u\n",
pin->work_pin_events_dropped_cnt);
seq_printf(file, "irq failed: %d\n", pin->enable_irq_failed);
if (pin->timer_100ms_overruns) {
seq_printf(file, "timer overruns > 100ms: %u of %u\n",
@ -1208,6 +1222,7 @@ static void cec_pin_adap_status(struct cec_adapter *adap,
pin->rx_data_bit_too_long_cnt);
seq_printf(file, "rx initiated low drive: %u\n", pin->rx_low_drive_cnt);
seq_printf(file, "tx detected low drive: %u\n", pin->tx_low_drive_cnt);
pin->work_pin_events_dropped_cnt = 0;
pin->timer_cnt = 0;
pin->timer_100ms_overruns = 0;
pin->timer_300ms_overruns = 0;

8
drivers/media/platform/vivid/vivid-cec.c
View File

@ -79,9 +79,9 @@ static void vivid_cec_pin_adap_events(struct cec_adapter *adap, ktime_t ts,
*/
ts = ktime_sub_us(ts, CEC_TIM_START_BIT_TOTAL +
10ULL * len * CEC_TIM_DATA_BIT_TOTAL);
cec_queue_pin_cec_event(adap, false, ts);
cec_queue_pin_cec_event(adap, false, false, ts);
ts = ktime_add_us(ts, CEC_TIM_START_BIT_LOW);
cec_queue_pin_cec_event(adap, true, ts);
cec_queue_pin_cec_event(adap, true, false, ts);
ts = ktime_add_us(ts, CEC_TIM_START_BIT_HIGH);
for (i = 0; i < 10 * len; i++) {
@ -96,12 +96,12 @@ static void vivid_cec_pin_adap_events(struct cec_adapter *adap, ktime_t ts,
bit = cec_msg_is_broadcast(msg) ^ nacked;
break;
}
cec_queue_pin_cec_event(adap, false, ts);
cec_queue_pin_cec_event(adap, false, false, ts);
if (bit)
ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_1_LOW);
else
ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_0_LOW);
cec_queue_pin_cec_event(adap, true, ts);
cec_queue_pin_cec_event(adap, true, false, ts);
if (bit)
ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_1_HIGH);
else

7
include/media/cec.h
View File

@ -92,7 +92,7 @@ struct cec_fh {
wait_queue_head_t wait;
struct mutex lock;
struct list_head events[CEC_NUM_EVENTS]; /* queued events */
u8 queued_events[CEC_NUM_EVENTS];
u16 queued_events[CEC_NUM_EVENTS];
unsigned int total_queued_events;
struct cec_event_entry core_events[CEC_NUM_CORE_EVENTS];
struct list_head msgs; /* queued messages */
@ -291,11 +291,12 @@ static inline void cec_received_msg(struct cec_adapter *adap,
*
* @adap: pointer to the cec adapter
* @is_high: when true the CEC pin is high, otherwise it is low
* @dropped_events: when true some events were dropped
* @ts: the timestamp for this event
*
*/
void cec_queue_pin_cec_event(struct cec_adapter *adap,
bool is_high, ktime_t ts);
void cec_queue_pin_cec_event(struct cec_adapter *adap, bool is_high,
bool dropped_events, ktime_t ts);
/**
* cec_queue_pin_hpd_event() - queue a pin event with a given timestamp.