| Message ID | 20210825084104.8387-1-deborahbrouwer3563@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] media: vivid: add signal-free time for cec message xfer | expand |
On 25/08/2021 10:41, Deborah Brouwer wrote: > Currently, the vivid emulation of cec message transmission does not force > adapters to wait until the cec bus has been signal-free for a certain > number of bit periods before transmitting or re-transmitting a message. > Without enforcing the signal-free time requirements, adapters do not share > the bus very well and some messages are sent too quickly while other > messages are lost. By emulating a signal-free time and forcing adapters > to wait their turn to transmit, the vivid emulation of cec transmission > is much more reliable. > > Signed-off-by: Deborah Brouwer <deborahbrouwer3563@gmail.com> > --- > Changes since v1: > - use actual message length instead of max when copying > - check for kthread_stop() within bus > - store the last_initiator in the vivid state > - update the last_initiator as soon as it is known and adjust sfts > - use last_initiator to assign sft when transmit is called > - use function for division > > drivers/media/test-drivers/vivid/vivid-cec.c | 341 ++++++++++-------- > drivers/media/test-drivers/vivid/vivid-cec.h | 9 +- > drivers/media/test-drivers/vivid/vivid-core.c | 37 +- > drivers/media/test-drivers/vivid/vivid-core.h | 23 +- > 4 files changed, 218 insertions(+), 192 deletions(-) > > diff --git a/drivers/media/test-drivers/vivid/vivid-cec.c b/drivers/media/test-drivers/vivid/vivid-cec.c > index 4d2413e87730..d97da4f10ad7 100644 > --- a/drivers/media/test-drivers/vivid/vivid-cec.c > +++ b/drivers/media/test-drivers/vivid/vivid-cec.c > @@ -5,40 +5,23 @@ > * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved. > */ > > +#include <linux/delay.h> > #include <media/cec.h> > > #include "vivid-core.h" > #include "vivid-cec.h" > > -#define CEC_TIM_START_BIT_TOTAL 4500 > -#define CEC_TIM_START_BIT_LOW 3700 > -#define CEC_TIM_START_BIT_HIGH 800 > -#define CEC_TIM_DATA_BIT_TOTAL 2400 > -#define CEC_TIM_DATA_BIT_0_LOW 1500 > -#define CEC_TIM_DATA_BIT_0_HIGH 900 > -#define CEC_TIM_DATA_BIT_1_LOW 600 > -#define CEC_TIM_DATA_BIT_1_HIGH 1800 > +#define CEC_START_BIT_US 4500 > +#define CEC_DATA_BIT_US 2400 > +#define CEC_MARGIN_US 350 > > -void vivid_cec_bus_free_work(struct vivid_dev *dev) > -{ > - spin_lock(&dev->cec_slock); > - while (!list_empty(&dev->cec_work_list)) { > - struct vivid_cec_work *cw = > - list_first_entry(&dev->cec_work_list, > - struct vivid_cec_work, list); > - > - spin_unlock(&dev->cec_slock); > - cancel_delayed_work_sync(&cw->work); > - spin_lock(&dev->cec_slock); > - list_del(&cw->list); > - cec_transmit_attempt_done(cw->adap, CEC_TX_STATUS_LOW_DRIVE); > - kfree(cw); > - } > - spin_unlock(&dev->cec_slock); > -} > +struct xfer_on_bus { > + struct cec_adapter *adap; > + u8 status; > +}; > > -static bool vivid_cec_find_dest_adap(struct vivid_dev *dev, > - struct cec_adapter *adap, u8 dest) > +static bool find_dest_adap(struct vivid_dev *dev, > + struct cec_adapter *adap, u8 dest) > { > unsigned int i; > > @@ -61,116 +44,187 @@ static bool vivid_cec_find_dest_adap(struct vivid_dev *dev, > return false; > } > > -static void vivid_cec_pin_adap_events(struct cec_adapter *adap, ktime_t ts, > - const struct cec_msg *msg, bool nacked) > +static bool xfer_ready(struct vivid_dev *dev) > { > - unsigned int len = nacked ? 1 : msg->len; > unsigned int i; > - bool bit; > - > - if (adap == NULL) > - return; > + bool ready = false; > > - /* > - * Suffix ULL on constant 10 makes the expression > - * CEC_TIM_START_BIT_TOTAL + 10ULL * len * CEC_TIM_DATA_BIT_TOTAL > - * to be evaluated using 64-bit unsigned arithmetic (u64), which > - * is what ktime_sub_us expects as second argument. > - */ > - ts = ktime_sub_us(ts, CEC_TIM_START_BIT_TOTAL + > - 10ULL * len * CEC_TIM_DATA_BIT_TOTAL); > - 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, false, ts); > - ts = ktime_add_us(ts, CEC_TIM_START_BIT_HIGH); > - > - for (i = 0; i < 10 * len; i++) { > - switch (i % 10) { > - case 0 ... 7: > - bit = msg->msg[i / 10] & (0x80 >> (i % 10)); > - break; > - case 8: /* EOM */ > - bit = i / 10 == msg->len - 1; > - break; > - case 9: /* ACK */ > - bit = cec_msg_is_broadcast(msg) ^ nacked; > + spin_lock(&dev->cec_xfers_slock); > + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { > + if (dev->xfers[i].sft && > + dev->xfers[i].sft <= dev->cec_sft) { > + ready = true; > break; > } > - 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, false, ts); > - if (bit) > - ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_1_HIGH); > - else > - ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_0_HIGH); > } > -} > + spin_unlock(&dev->cec_xfers_slock); > > -static void vivid_cec_pin_events(struct vivid_dev *dev, > - const struct cec_msg *msg, bool nacked) > -{ > - ktime_t ts = ktime_get(); > - unsigned int i; > - > - vivid_cec_pin_adap_events(dev->cec_rx_adap, ts, msg, nacked); > - for (i = 0; i < MAX_OUTPUTS; i++) > - vivid_cec_pin_adap_events(dev->cec_tx_adap[i], ts, msg, nacked); > + return ready; > } > > -static void vivid_cec_xfer_done_worker(struct work_struct *work) > +/* > + * If an adapter tries to send successive messages, it must wait for the > + * longest signal-free time between its transmissions. But, if another > + * adapter sends a message in the interim, then the wait can be reduced > + * because the messages are no longer successive. Make these adjustments > + * if necessary. Should be called holding cec_xfers_slock. > + */ > +static void adjust_sfts(struct vivid_dev *dev) > { > - struct vivid_cec_work *cw = > - container_of(work, struct vivid_cec_work, work.work); > - struct vivid_dev *dev = cw->dev; > - struct cec_adapter *adap = cw->adap; > - u8 dest = cec_msg_destination(&cw->msg); > - bool valid_dest; > unsigned int i; > + u8 initiator; > > - valid_dest = cec_msg_is_broadcast(&cw->msg); > - if (!valid_dest) > - valid_dest = vivid_cec_find_dest_adap(dev, adap, dest); > - > - cw->tx_status = valid_dest ? CEC_TX_STATUS_OK : CEC_TX_STATUS_NACK; > - spin_lock(&dev->cec_slock); > - dev->cec_xfer_time_jiffies = 0; > - dev->cec_xfer_start_jiffies = 0; > - list_del(&cw->list); > - spin_unlock(&dev->cec_slock); > - vivid_cec_pin_events(dev, &cw->msg, !valid_dest); > - cec_transmit_attempt_done(cw->adap, cw->tx_status); > - > - /* Broadcast message */ > - if (adap != dev->cec_rx_adap) > - cec_received_msg(dev->cec_rx_adap, &cw->msg); > - for (i = 0; i < MAX_OUTPUTS && dev->cec_tx_adap[i]; i++) > - if (adap != dev->cec_tx_adap[i]) > - cec_received_msg(dev->cec_tx_adap[i], &cw->msg); > - kfree(cw); > + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { > + if (dev->xfers[i].sft <= CEC_SIGNAL_FREE_TIME_RETRY) > + continue; > + initiator = dev->xfers[i].msg[0] >> 4; > + if (initiator == dev->last_initiator) > + dev->xfers[i].sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; > + else > + dev->xfers[i].sft = CEC_SIGNAL_FREE_TIME_NEW_INITIATOR; > + } > } > > -static void vivid_cec_xfer_try_worker(struct work_struct *work) > +/* > + * The main emulation of the bus on which CEC adapters attempt to send > + * messages to each other. The bus keeps track of how long it has been > + * signal-free and accepts a pending transmission only if the state of > + * the bus matches the transmission's signal-free requirements. It calls > + * cec_transmit_attempt_done() for all transmits that enter the bus and > + * cec_received_msg() for successful transmits. > + */ > +int vivid_cec_bus_thread(void *_dev) > { > - struct vivid_cec_work *cw = > - container_of(work, struct vivid_cec_work, work.work); > - struct vivid_dev *dev = cw->dev; > - > - spin_lock(&dev->cec_slock); > - if (dev->cec_xfer_time_jiffies) { > - list_del(&cw->list); > - spin_unlock(&dev->cec_slock); > - cec_transmit_attempt_done(cw->adap, CEC_TX_STATUS_ARB_LOST); > - kfree(cw); > - } else { > - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_done_worker); > - dev->cec_xfer_start_jiffies = jiffies; > - dev->cec_xfer_time_jiffies = usecs_to_jiffies(cw->usecs); > - spin_unlock(&dev->cec_slock); > - schedule_delayed_work(&cw->work, dev->cec_xfer_time_jiffies); > + u32 last_sft; > + unsigned int i; > + unsigned int dest; > + ktime_t start, end; > + s64 delta_us, retry_us; > + unsigned int first_idx; > + unsigned int first_status; > + struct vivid_dev *dev = _dev; > + > + dev->cec_sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; > + for (;;) { > + bool first = true; > + int wait_xfer_us = 0; > + bool valid_dest = false; > + int wait_arb_lost_us = 0; > + struct cec_msg first_msg = {}; > + struct xfer_on_bus xfers_on_bus[MAX_OUTPUTS] = {}; > + > + wait_event_interruptible(dev->kthread_waitq_cec, xfer_ready(dev) || > + kthread_should_stop()); > + if (kthread_should_stop()) > + break; > + last_sft = dev->cec_sft; > + dev->cec_sft = 0; > + /* > + * Move the messages that are ready onto the bus. The adapter with > + * the most leading zeros will win control of the bus and any other > + * adapters will lose arbitration. > + */ > + spin_lock(&dev->cec_xfers_slock); > + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { > + if (!dev->xfers[i].sft || dev->xfers[i].sft > last_sft) > + continue; > + if (first) { > + first = false; > + first_idx = i; > + xfers_on_bus[first_idx].adap = dev->xfers[i].adap; > + memcpy(first_msg.msg, dev->xfers[i].msg, dev->xfers[i].len); > + first_msg.len = dev->xfers[i].len; > + } else { > + xfers_on_bus[i].adap = dev->xfers[i].adap; > + xfers_on_bus[i].status = CEC_TX_STATUS_ARB_LOST; > + /* > + * For simplicity wait for all 4 bits of the initiator's > + * address even though HDMI specification uses bit-level > + * precision. > + */ > + wait_arb_lost_us = 4 * CEC_DATA_BIT_US + CEC_START_BIT_US; > + } > + dev->xfers[i].sft = 0; > + } > + dev->last_initiator = cec_msg_initiator(&first_msg); > + adjust_sfts(dev); > + spin_unlock(&dev->cec_xfers_slock); > + > + dest = cec_msg_destination(&first_msg); > + valid_dest = cec_msg_is_broadcast(&first_msg); > + if (!valid_dest) > + valid_dest = find_dest_adap(dev, xfers_on_bus[first_idx].adap, dest); > + if (valid_dest) { > + first_status = CEC_TX_STATUS_OK; > + /* > + * Message length is in bytes, but each byte is transmitted in > + * a block of 10 bits. > + */ > + wait_xfer_us = first_msg.len * 10 * CEC_DATA_BIT_US; > + } else { > + first_status = CEC_TX_STATUS_NACK; > + /* > + * A message that is not acknowledged stops transmitting after > + * the header block of 10 bits. > + */ > + wait_xfer_us = 10 * CEC_DATA_BIT_US; > + } > + wait_xfer_us += CEC_START_BIT_US; > + xfers_on_bus[first_idx].status = first_status; I'm getting this compiler warning: vivid-cec.c:190:3: warning: 'first_idx' may be used uninitialized in this function [-Wmaybe-uninitialized] The compiler isn't quite smart enough to figure out that first_idx will always be initialized, but it is still a good idea to just initialize first_idx to 0. I would also move the first_idx and first_status variables into the for-loop as well, after the 'bool first' variable. > + > + /* Sleep as if sending messages on a real hardware bus. */ > + start = ktime_get(); > + if (wait_arb_lost_us) { > + usleep_range(wait_arb_lost_us - CEC_MARGIN_US, wait_arb_lost_us); > + for (i = 0; i < ARRAY_SIZE(xfers_on_bus); i++) { > + if (xfers_on_bus[i].status != CEC_TX_STATUS_ARB_LOST) > + continue; > + cec_transmit_attempt_done(xfers_on_bus[i].adap, > + CEC_TX_STATUS_ARB_LOST); > + } > + if (kthread_should_stop()) > + break; > + } > + wait_xfer_us -= wait_arb_lost_us; > + usleep_range(wait_xfer_us - CEC_MARGIN_US, wait_xfer_us); > + cec_transmit_attempt_done(xfers_on_bus[first_idx].adap, first_status); > + if (kthread_should_stop()) > + break; > + if (first_status == CEC_TX_STATUS_OK) { > + if (xfers_on_bus[first_idx].adap != dev->cec_rx_adap) > + cec_received_msg(dev->cec_rx_adap, &first_msg); > + for (i = 0; i < MAX_OUTPUTS && dev->cec_tx_adap[i]; i++) > + if (xfers_on_bus[first_idx].adap != dev->cec_tx_adap[i]) > + cec_received_msg(dev->cec_tx_adap[i], &first_msg); > + } > + end = ktime_get(); > + /* > + * If the emulated transfer took more or less time than it should > + * have, then compensate by adjusting the wait time needed for the > + * bus to be signal-free for 3 bit periods (the retry time). > + */ > + delta_us = div_s64(end - start, 1000); > + delta_us -= wait_xfer_us + wait_arb_lost_us; > + retry_us = CEC_SIGNAL_FREE_TIME_RETRY * CEC_DATA_BIT_US - delta_us; > + if (retry_us > CEC_MARGIN_US) > + usleep_range(retry_us - CEC_MARGIN_US, retry_us); > + dev->cec_sft = CEC_SIGNAL_FREE_TIME_RETRY; > + /* > + * If there are no messages that need to be retried, check if any > + * adapters that did not just transmit a message are ready to > + * transmit. If none of these adapters are ready, then increase > + * the signal-free time so that the bus is available to all > + * adapters and go back to waiting for a transmission. > + */ > + while (dev->cec_sft >= CEC_SIGNAL_FREE_TIME_RETRY && > + dev->cec_sft < CEC_SIGNAL_FREE_TIME_NEXT_XFER && > + !xfer_ready(dev) && !kthread_should_stop()) { > + usleep_range(2 * CEC_DATA_BIT_US - CEC_MARGIN_US, > + 2 * CEC_DATA_BIT_US); > + dev->cec_sft += 2; > + } > } > + return 0; > } > > static int vivid_cec_adap_enable(struct cec_adapter *adap, bool enable) > @@ -184,41 +238,26 @@ static int vivid_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr) > return 0; > } > > -/* > - * One data bit takes 2400 us, each byte needs 10 bits so that's 24000 us > - * per byte. > - */ > -#define USECS_PER_BYTE 24000 > - > static int vivid_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, > u32 signal_free_time, struct cec_msg *msg) > { > struct vivid_dev *dev = cec_get_drvdata(adap); > - struct vivid_cec_work *cw = kzalloc(sizeof(*cw), GFP_KERNEL); > - long delta_jiffies = 0; > - > - if (cw == NULL) > - return -ENOMEM; > - cw->dev = dev; > - cw->adap = adap; > - cw->usecs = CEC_FREE_TIME_TO_USEC(signal_free_time) + > - msg->len * USECS_PER_BYTE; > - cw->msg = *msg; > - > - spin_lock(&dev->cec_slock); > - list_add(&cw->list, &dev->cec_work_list); > - if (dev->cec_xfer_time_jiffies == 0) { > - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_done_worker); > - dev->cec_xfer_start_jiffies = jiffies; > - dev->cec_xfer_time_jiffies = usecs_to_jiffies(cw->usecs); > - delta_jiffies = dev->cec_xfer_time_jiffies; > - } else { > - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_try_worker); > - delta_jiffies = dev->cec_xfer_start_jiffies + > - dev->cec_xfer_time_jiffies - jiffies; > + u8 idx = cec_msg_initiator(msg); > + > + spin_lock(&dev->cec_xfers_slock); > + dev->xfers[idx].adap = adap; > + memcpy(dev->xfers[idx].msg, msg->msg, CEC_MAX_MSG_SIZE); > + dev->xfers[idx].len = msg->len; > + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_RETRY; > + if (signal_free_time > CEC_SIGNAL_FREE_TIME_RETRY) { > + if (idx == dev->last_initiator) > + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; > + else > + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_NEW_INITIATOR; > } > - spin_unlock(&dev->cec_slock); > - schedule_delayed_work(&cw->work, delta_jiffies < 0 ? 0 : delta_jiffies); > + spin_unlock(&dev->cec_xfers_slock); > + wake_up_interruptible(&dev->kthread_waitq_cec); > + > return 0; > } > > diff --git a/drivers/media/test-drivers/vivid/vivid-cec.h b/drivers/media/test-drivers/vivid/vivid-cec.h > index 7524ed48a914..b2bcddb50b83 100644 > --- a/drivers/media/test-drivers/vivid/vivid-cec.h > +++ b/drivers/media/test-drivers/vivid/vivid-cec.h > @@ -9,12 +9,5 @@ > struct cec_adapter *vivid_cec_alloc_adap(struct vivid_dev *dev, > unsigned int idx, > bool is_source); > -void vivid_cec_bus_free_work(struct vivid_dev *dev); > - > -#else > - > -static inline void vivid_cec_bus_free_work(struct vivid_dev *dev) > -{ > -} > - > +int vivid_cec_bus_thread(void *_dev); > #endif > diff --git a/drivers/media/test-drivers/vivid/vivid-core.c b/drivers/media/test-drivers/vivid/vivid-core.c > index d2bd2653cf54..1973e08953ab 100644 > --- a/drivers/media/test-drivers/vivid/vivid-core.c > +++ b/drivers/media/test-drivers/vivid/vivid-core.c > @@ -1878,18 +1878,7 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) > INIT_LIST_HEAD(&dev->meta_out_active); > INIT_LIST_HEAD(&dev->touch_cap_active); > > - INIT_LIST_HEAD(&dev->cec_work_list); > - spin_lock_init(&dev->cec_slock); > - /* > - * Same as create_singlethread_workqueue, but now I can use the > - * string formatting of alloc_ordered_workqueue. > - */ > - dev->cec_workqueue = alloc_ordered_workqueue("vivid-%03d-cec", > - WQ_MEM_RECLAIM, inst); > - if (!dev->cec_workqueue) { > - ret = -ENOMEM; > - goto unreg_dev; > - } > + spin_lock_init(&dev->cec_xfers_slock); > > if (allocators[inst] == 1) > dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); > @@ -1929,6 +1918,18 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) > cec_tx_bus_cnt++; > } > } > + > + if (dev->cec_rx_adap || cec_tx_bus_cnt) { > + init_waitqueue_head(&dev->kthread_waitq_cec); > + dev->kthread_cec = kthread_run(vivid_cec_bus_thread, dev, > + "vivid_cec-%s", dev->v4l2_dev.name); > + if (IS_ERR(dev->kthread_cec)) { > + dev->kthread_cec = NULL; > + v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n"); You should this line here: ret = PTR_ERR(dev->kthread_cec); to correctly propagate the kthread_run error code. Regards, Hans > + goto unreg_dev; > + } > + } > + > #endif > > v4l2_ctrl_handler_setup(&dev->ctrl_hdl_vid_cap); > @@ -1968,10 +1969,8 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) > cec_unregister_adapter(dev->cec_rx_adap); > for (i = 0; i < MAX_OUTPUTS; i++) > cec_unregister_adapter(dev->cec_tx_adap[i]); > - if (dev->cec_workqueue) { > - vivid_cec_bus_free_work(dev); > - destroy_workqueue(dev->cec_workqueue); > - } > + if (dev->kthread_cec) > + kthread_stop(dev->kthread_cec); > free_dev: > v4l2_device_put(&dev->v4l2_dev); > return ret; > @@ -2093,10 +2092,8 @@ static int vivid_remove(struct platform_device *pdev) > cec_unregister_adapter(dev->cec_rx_adap); > for (j = 0; j < MAX_OUTPUTS; j++) > cec_unregister_adapter(dev->cec_tx_adap[j]); > - if (dev->cec_workqueue) { > - vivid_cec_bus_free_work(dev); > - destroy_workqueue(dev->cec_workqueue); > - } > + if (dev->kthread_cec) > + kthread_stop(dev->kthread_cec); > v4l2_device_put(&dev->v4l2_dev); > vivid_devs[i] = NULL; > } > diff --git a/drivers/media/test-drivers/vivid/vivid-core.h b/drivers/media/test-drivers/vivid/vivid-core.h > index 1e3c4f5a9413..45f96706edde 100644 > --- a/drivers/media/test-drivers/vivid/vivid-core.h > +++ b/drivers/media/test-drivers/vivid/vivid-core.h > @@ -110,15 +110,11 @@ enum vivid_colorspace { > #define VIVID_INVALID_SIGNAL(mode) \ > ((mode) == NO_SIGNAL || (mode) == NO_LOCK || (mode) == OUT_OF_RANGE) > > -struct vivid_cec_work { > - struct list_head list; > - struct delayed_work work; > +struct vivid_cec_xfer { > struct cec_adapter *adap; > - struct vivid_dev *dev; > - unsigned int usecs; > - unsigned int timeout_ms; > - u8 tx_status; > - struct cec_msg msg; > + u8 msg[CEC_MAX_MSG_SIZE]; > + u32 len; > + u32 sft; > }; > > struct vivid_dev { > @@ -560,12 +556,13 @@ struct vivid_dev { > /* CEC */ > struct cec_adapter *cec_rx_adap; > struct cec_adapter *cec_tx_adap[MAX_OUTPUTS]; > - struct workqueue_struct *cec_workqueue; > - spinlock_t cec_slock; > - struct list_head cec_work_list; > - unsigned int cec_xfer_time_jiffies; > - unsigned long cec_xfer_start_jiffies; > u8 cec_output2bus_map[MAX_OUTPUTS]; > + struct task_struct *kthread_cec; > + wait_queue_head_t kthread_waitq_cec; > + struct vivid_cec_xfer xfers[MAX_OUTPUTS]; > + spinlock_t cec_xfers_slock; /* read and write cec messages */ > + u32 cec_sft; /* bus signal free time, in bit periods */ > + u8 last_initiator; > > /* CEC OSD String */ > char osd[14]; >
diff --git a/drivers/media/test-drivers/vivid/vivid-cec.c b/drivers/media/test-drivers/vivid/vivid-cec.c index 4d2413e87730..d97da4f10ad7 100644 --- a/drivers/media/test-drivers/vivid/vivid-cec.c +++ b/drivers/media/test-drivers/vivid/vivid-cec.c @@ -5,40 +5,23 @@ * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved. */ +#include <linux/delay.h> #include <media/cec.h> #include "vivid-core.h" #include "vivid-cec.h" -#define CEC_TIM_START_BIT_TOTAL 4500 -#define CEC_TIM_START_BIT_LOW 3700 -#define CEC_TIM_START_BIT_HIGH 800 -#define CEC_TIM_DATA_BIT_TOTAL 2400 -#define CEC_TIM_DATA_BIT_0_LOW 1500 -#define CEC_TIM_DATA_BIT_0_HIGH 900 -#define CEC_TIM_DATA_BIT_1_LOW 600 -#define CEC_TIM_DATA_BIT_1_HIGH 1800 +#define CEC_START_BIT_US 4500 +#define CEC_DATA_BIT_US 2400 +#define CEC_MARGIN_US 350 -void vivid_cec_bus_free_work(struct vivid_dev *dev) -{ - spin_lock(&dev->cec_slock); - while (!list_empty(&dev->cec_work_list)) { - struct vivid_cec_work *cw = - list_first_entry(&dev->cec_work_list, - struct vivid_cec_work, list); - - spin_unlock(&dev->cec_slock); - cancel_delayed_work_sync(&cw->work); - spin_lock(&dev->cec_slock); - list_del(&cw->list); - cec_transmit_attempt_done(cw->adap, CEC_TX_STATUS_LOW_DRIVE); - kfree(cw); - } - spin_unlock(&dev->cec_slock); -} +struct xfer_on_bus { + struct cec_adapter *adap; + u8 status; +}; -static bool vivid_cec_find_dest_adap(struct vivid_dev *dev, - struct cec_adapter *adap, u8 dest) +static bool find_dest_adap(struct vivid_dev *dev, + struct cec_adapter *adap, u8 dest) { unsigned int i; @@ -61,116 +44,187 @@ static bool vivid_cec_find_dest_adap(struct vivid_dev *dev, return false; } -static void vivid_cec_pin_adap_events(struct cec_adapter *adap, ktime_t ts, - const struct cec_msg *msg, bool nacked) +static bool xfer_ready(struct vivid_dev *dev) { - unsigned int len = nacked ? 1 : msg->len; unsigned int i; - bool bit; - - if (adap == NULL) - return; + bool ready = false; - /* - * Suffix ULL on constant 10 makes the expression - * CEC_TIM_START_BIT_TOTAL + 10ULL * len * CEC_TIM_DATA_BIT_TOTAL - * to be evaluated using 64-bit unsigned arithmetic (u64), which - * is what ktime_sub_us expects as second argument. - */ - ts = ktime_sub_us(ts, CEC_TIM_START_BIT_TOTAL + - 10ULL * len * CEC_TIM_DATA_BIT_TOTAL); - 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, false, ts); - ts = ktime_add_us(ts, CEC_TIM_START_BIT_HIGH); - - for (i = 0; i < 10 * len; i++) { - switch (i % 10) { - case 0 ... 7: - bit = msg->msg[i / 10] & (0x80 >> (i % 10)); - break; - case 8: /* EOM */ - bit = i / 10 == msg->len - 1; - break; - case 9: /* ACK */ - bit = cec_msg_is_broadcast(msg) ^ nacked; + spin_lock(&dev->cec_xfers_slock); + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { + if (dev->xfers[i].sft && + dev->xfers[i].sft <= dev->cec_sft) { + ready = true; break; } - 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, false, ts); - if (bit) - ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_1_HIGH); - else - ts = ktime_add_us(ts, CEC_TIM_DATA_BIT_0_HIGH); } -} + spin_unlock(&dev->cec_xfers_slock); -static void vivid_cec_pin_events(struct vivid_dev *dev, - const struct cec_msg *msg, bool nacked) -{ - ktime_t ts = ktime_get(); - unsigned int i; - - vivid_cec_pin_adap_events(dev->cec_rx_adap, ts, msg, nacked); - for (i = 0; i < MAX_OUTPUTS; i++) - vivid_cec_pin_adap_events(dev->cec_tx_adap[i], ts, msg, nacked); + return ready; } -static void vivid_cec_xfer_done_worker(struct work_struct *work) +/* + * If an adapter tries to send successive messages, it must wait for the + * longest signal-free time between its transmissions. But, if another + * adapter sends a message in the interim, then the wait can be reduced + * because the messages are no longer successive. Make these adjustments + * if necessary. Should be called holding cec_xfers_slock. + */ +static void adjust_sfts(struct vivid_dev *dev) { - struct vivid_cec_work *cw = - container_of(work, struct vivid_cec_work, work.work); - struct vivid_dev *dev = cw->dev; - struct cec_adapter *adap = cw->adap; - u8 dest = cec_msg_destination(&cw->msg); - bool valid_dest; unsigned int i; + u8 initiator; - valid_dest = cec_msg_is_broadcast(&cw->msg); - if (!valid_dest) - valid_dest = vivid_cec_find_dest_adap(dev, adap, dest); - - cw->tx_status = valid_dest ? CEC_TX_STATUS_OK : CEC_TX_STATUS_NACK; - spin_lock(&dev->cec_slock); - dev->cec_xfer_time_jiffies = 0; - dev->cec_xfer_start_jiffies = 0; - list_del(&cw->list); - spin_unlock(&dev->cec_slock); - vivid_cec_pin_events(dev, &cw->msg, !valid_dest); - cec_transmit_attempt_done(cw->adap, cw->tx_status); - - /* Broadcast message */ - if (adap != dev->cec_rx_adap) - cec_received_msg(dev->cec_rx_adap, &cw->msg); - for (i = 0; i < MAX_OUTPUTS && dev->cec_tx_adap[i]; i++) - if (adap != dev->cec_tx_adap[i]) - cec_received_msg(dev->cec_tx_adap[i], &cw->msg); - kfree(cw); + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { + if (dev->xfers[i].sft <= CEC_SIGNAL_FREE_TIME_RETRY) + continue; + initiator = dev->xfers[i].msg[0] >> 4; + if (initiator == dev->last_initiator) + dev->xfers[i].sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; + else + dev->xfers[i].sft = CEC_SIGNAL_FREE_TIME_NEW_INITIATOR; + } } -static void vivid_cec_xfer_try_worker(struct work_struct *work) +/* + * The main emulation of the bus on which CEC adapters attempt to send + * messages to each other. The bus keeps track of how long it has been + * signal-free and accepts a pending transmission only if the state of + * the bus matches the transmission's signal-free requirements. It calls + * cec_transmit_attempt_done() for all transmits that enter the bus and + * cec_received_msg() for successful transmits. + */ +int vivid_cec_bus_thread(void *_dev) { - struct vivid_cec_work *cw = - container_of(work, struct vivid_cec_work, work.work); - struct vivid_dev *dev = cw->dev; - - spin_lock(&dev->cec_slock); - if (dev->cec_xfer_time_jiffies) { - list_del(&cw->list); - spin_unlock(&dev->cec_slock); - cec_transmit_attempt_done(cw->adap, CEC_TX_STATUS_ARB_LOST); - kfree(cw); - } else { - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_done_worker); - dev->cec_xfer_start_jiffies = jiffies; - dev->cec_xfer_time_jiffies = usecs_to_jiffies(cw->usecs); - spin_unlock(&dev->cec_slock); - schedule_delayed_work(&cw->work, dev->cec_xfer_time_jiffies); + u32 last_sft; + unsigned int i; + unsigned int dest; + ktime_t start, end; + s64 delta_us, retry_us; + unsigned int first_idx; + unsigned int first_status; + struct vivid_dev *dev = _dev; + + dev->cec_sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; + for (;;) { + bool first = true; + int wait_xfer_us = 0; + bool valid_dest = false; + int wait_arb_lost_us = 0; + struct cec_msg first_msg = {}; + struct xfer_on_bus xfers_on_bus[MAX_OUTPUTS] = {}; + + wait_event_interruptible(dev->kthread_waitq_cec, xfer_ready(dev) || + kthread_should_stop()); + if (kthread_should_stop()) + break; + last_sft = dev->cec_sft; + dev->cec_sft = 0; + /* + * Move the messages that are ready onto the bus. The adapter with + * the most leading zeros will win control of the bus and any other + * adapters will lose arbitration. + */ + spin_lock(&dev->cec_xfers_slock); + for (i = 0; i < ARRAY_SIZE(dev->xfers); i++) { + if (!dev->xfers[i].sft || dev->xfers[i].sft > last_sft) + continue; + if (first) { + first = false; + first_idx = i; + xfers_on_bus[first_idx].adap = dev->xfers[i].adap; + memcpy(first_msg.msg, dev->xfers[i].msg, dev->xfers[i].len); + first_msg.len = dev->xfers[i].len; + } else { + xfers_on_bus[i].adap = dev->xfers[i].adap; + xfers_on_bus[i].status = CEC_TX_STATUS_ARB_LOST; + /* + * For simplicity wait for all 4 bits of the initiator's + * address even though HDMI specification uses bit-level + * precision. + */ + wait_arb_lost_us = 4 * CEC_DATA_BIT_US + CEC_START_BIT_US; + } + dev->xfers[i].sft = 0; + } + dev->last_initiator = cec_msg_initiator(&first_msg); + adjust_sfts(dev); + spin_unlock(&dev->cec_xfers_slock); + + dest = cec_msg_destination(&first_msg); + valid_dest = cec_msg_is_broadcast(&first_msg); + if (!valid_dest) + valid_dest = find_dest_adap(dev, xfers_on_bus[first_idx].adap, dest); + if (valid_dest) { + first_status = CEC_TX_STATUS_OK; + /* + * Message length is in bytes, but each byte is transmitted in + * a block of 10 bits. + */ + wait_xfer_us = first_msg.len * 10 * CEC_DATA_BIT_US; + } else { + first_status = CEC_TX_STATUS_NACK; + /* + * A message that is not acknowledged stops transmitting after + * the header block of 10 bits. + */ + wait_xfer_us = 10 * CEC_DATA_BIT_US; + } + wait_xfer_us += CEC_START_BIT_US; + xfers_on_bus[first_idx].status = first_status; + + /* Sleep as if sending messages on a real hardware bus. */ + start = ktime_get(); + if (wait_arb_lost_us) { + usleep_range(wait_arb_lost_us - CEC_MARGIN_US, wait_arb_lost_us); + for (i = 0; i < ARRAY_SIZE(xfers_on_bus); i++) { + if (xfers_on_bus[i].status != CEC_TX_STATUS_ARB_LOST) + continue; + cec_transmit_attempt_done(xfers_on_bus[i].adap, + CEC_TX_STATUS_ARB_LOST); + } + if (kthread_should_stop()) + break; + } + wait_xfer_us -= wait_arb_lost_us; + usleep_range(wait_xfer_us - CEC_MARGIN_US, wait_xfer_us); + cec_transmit_attempt_done(xfers_on_bus[first_idx].adap, first_status); + if (kthread_should_stop()) + break; + if (first_status == CEC_TX_STATUS_OK) { + if (xfers_on_bus[first_idx].adap != dev->cec_rx_adap) + cec_received_msg(dev->cec_rx_adap, &first_msg); + for (i = 0; i < MAX_OUTPUTS && dev->cec_tx_adap[i]; i++) + if (xfers_on_bus[first_idx].adap != dev->cec_tx_adap[i]) + cec_received_msg(dev->cec_tx_adap[i], &first_msg); + } + end = ktime_get(); + /* + * If the emulated transfer took more or less time than it should + * have, then compensate by adjusting the wait time needed for the + * bus to be signal-free for 3 bit periods (the retry time). + */ + delta_us = div_s64(end - start, 1000); + delta_us -= wait_xfer_us + wait_arb_lost_us; + retry_us = CEC_SIGNAL_FREE_TIME_RETRY * CEC_DATA_BIT_US - delta_us; + if (retry_us > CEC_MARGIN_US) + usleep_range(retry_us - CEC_MARGIN_US, retry_us); + dev->cec_sft = CEC_SIGNAL_FREE_TIME_RETRY; + /* + * If there are no messages that need to be retried, check if any + * adapters that did not just transmit a message are ready to + * transmit. If none of these adapters are ready, then increase + * the signal-free time so that the bus is available to all + * adapters and go back to waiting for a transmission. + */ + while (dev->cec_sft >= CEC_SIGNAL_FREE_TIME_RETRY && + dev->cec_sft < CEC_SIGNAL_FREE_TIME_NEXT_XFER && + !xfer_ready(dev) && !kthread_should_stop()) { + usleep_range(2 * CEC_DATA_BIT_US - CEC_MARGIN_US, + 2 * CEC_DATA_BIT_US); + dev->cec_sft += 2; + } } + return 0; } static int vivid_cec_adap_enable(struct cec_adapter *adap, bool enable) @@ -184,41 +238,26 @@ static int vivid_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr) return 0; } -/* - * One data bit takes 2400 us, each byte needs 10 bits so that's 24000 us - * per byte. - */ -#define USECS_PER_BYTE 24000 - static int vivid_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, u32 signal_free_time, struct cec_msg *msg) { struct vivid_dev *dev = cec_get_drvdata(adap); - struct vivid_cec_work *cw = kzalloc(sizeof(*cw), GFP_KERNEL); - long delta_jiffies = 0; - - if (cw == NULL) - return -ENOMEM; - cw->dev = dev; - cw->adap = adap; - cw->usecs = CEC_FREE_TIME_TO_USEC(signal_free_time) + - msg->len * USECS_PER_BYTE; - cw->msg = *msg; - - spin_lock(&dev->cec_slock); - list_add(&cw->list, &dev->cec_work_list); - if (dev->cec_xfer_time_jiffies == 0) { - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_done_worker); - dev->cec_xfer_start_jiffies = jiffies; - dev->cec_xfer_time_jiffies = usecs_to_jiffies(cw->usecs); - delta_jiffies = dev->cec_xfer_time_jiffies; - } else { - INIT_DELAYED_WORK(&cw->work, vivid_cec_xfer_try_worker); - delta_jiffies = dev->cec_xfer_start_jiffies + - dev->cec_xfer_time_jiffies - jiffies; + u8 idx = cec_msg_initiator(msg); + + spin_lock(&dev->cec_xfers_slock); + dev->xfers[idx].adap = adap; + memcpy(dev->xfers[idx].msg, msg->msg, CEC_MAX_MSG_SIZE); + dev->xfers[idx].len = msg->len; + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_RETRY; + if (signal_free_time > CEC_SIGNAL_FREE_TIME_RETRY) { + if (idx == dev->last_initiator) + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_NEXT_XFER; + else + dev->xfers[idx].sft = CEC_SIGNAL_FREE_TIME_NEW_INITIATOR; } - spin_unlock(&dev->cec_slock); - schedule_delayed_work(&cw->work, delta_jiffies < 0 ? 0 : delta_jiffies); + spin_unlock(&dev->cec_xfers_slock); + wake_up_interruptible(&dev->kthread_waitq_cec); + return 0; } diff --git a/drivers/media/test-drivers/vivid/vivid-cec.h b/drivers/media/test-drivers/vivid/vivid-cec.h index 7524ed48a914..b2bcddb50b83 100644 --- a/drivers/media/test-drivers/vivid/vivid-cec.h +++ b/drivers/media/test-drivers/vivid/vivid-cec.h @@ -9,12 +9,5 @@ struct cec_adapter *vivid_cec_alloc_adap(struct vivid_dev *dev, unsigned int idx, bool is_source); -void vivid_cec_bus_free_work(struct vivid_dev *dev); - -#else - -static inline void vivid_cec_bus_free_work(struct vivid_dev *dev) -{ -} - +int vivid_cec_bus_thread(void *_dev); #endif diff --git a/drivers/media/test-drivers/vivid/vivid-core.c b/drivers/media/test-drivers/vivid/vivid-core.c index d2bd2653cf54..1973e08953ab 100644 --- a/drivers/media/test-drivers/vivid/vivid-core.c +++ b/drivers/media/test-drivers/vivid/vivid-core.c @@ -1878,18 +1878,7 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) INIT_LIST_HEAD(&dev->meta_out_active); INIT_LIST_HEAD(&dev->touch_cap_active); - INIT_LIST_HEAD(&dev->cec_work_list); - spin_lock_init(&dev->cec_slock); - /* - * Same as create_singlethread_workqueue, but now I can use the - * string formatting of alloc_ordered_workqueue. - */ - dev->cec_workqueue = alloc_ordered_workqueue("vivid-%03d-cec", - WQ_MEM_RECLAIM, inst); - if (!dev->cec_workqueue) { - ret = -ENOMEM; - goto unreg_dev; - } + spin_lock_init(&dev->cec_xfers_slock); if (allocators[inst] == 1) dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); @@ -1929,6 +1918,18 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) cec_tx_bus_cnt++; } } + + if (dev->cec_rx_adap || cec_tx_bus_cnt) { + init_waitqueue_head(&dev->kthread_waitq_cec); + dev->kthread_cec = kthread_run(vivid_cec_bus_thread, dev, + "vivid_cec-%s", dev->v4l2_dev.name); + if (IS_ERR(dev->kthread_cec)) { + dev->kthread_cec = NULL; + v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n"); + goto unreg_dev; + } + } + #endif v4l2_ctrl_handler_setup(&dev->ctrl_hdl_vid_cap); @@ -1968,10 +1969,8 @@ static int vivid_create_instance(struct platform_device *pdev, int inst) cec_unregister_adapter(dev->cec_rx_adap); for (i = 0; i < MAX_OUTPUTS; i++) cec_unregister_adapter(dev->cec_tx_adap[i]); - if (dev->cec_workqueue) { - vivid_cec_bus_free_work(dev); - destroy_workqueue(dev->cec_workqueue); - } + if (dev->kthread_cec) + kthread_stop(dev->kthread_cec); free_dev: v4l2_device_put(&dev->v4l2_dev); return ret; @@ -2093,10 +2092,8 @@ static int vivid_remove(struct platform_device *pdev) cec_unregister_adapter(dev->cec_rx_adap); for (j = 0; j < MAX_OUTPUTS; j++) cec_unregister_adapter(dev->cec_tx_adap[j]); - if (dev->cec_workqueue) { - vivid_cec_bus_free_work(dev); - destroy_workqueue(dev->cec_workqueue); - } + if (dev->kthread_cec) + kthread_stop(dev->kthread_cec); v4l2_device_put(&dev->v4l2_dev); vivid_devs[i] = NULL; } diff --git a/drivers/media/test-drivers/vivid/vivid-core.h b/drivers/media/test-drivers/vivid/vivid-core.h index 1e3c4f5a9413..45f96706edde 100644 --- a/drivers/media/test-drivers/vivid/vivid-core.h +++ b/drivers/media/test-drivers/vivid/vivid-core.h @@ -110,15 +110,11 @@ enum vivid_colorspace { #define VIVID_INVALID_SIGNAL(mode) \ ((mode) == NO_SIGNAL || (mode) == NO_LOCK || (mode) == OUT_OF_RANGE) -struct vivid_cec_work { - struct list_head list; - struct delayed_work work; +struct vivid_cec_xfer { struct cec_adapter *adap; - struct vivid_dev *dev; - unsigned int usecs; - unsigned int timeout_ms; - u8 tx_status; - struct cec_msg msg; + u8 msg[CEC_MAX_MSG_SIZE]; + u32 len; + u32 sft; }; struct vivid_dev { @@ -560,12 +556,13 @@ struct vivid_dev { /* CEC */ struct cec_adapter *cec_rx_adap; struct cec_adapter *cec_tx_adap[MAX_OUTPUTS]; - struct workqueue_struct *cec_workqueue; - spinlock_t cec_slock; - struct list_head cec_work_list; - unsigned int cec_xfer_time_jiffies; - unsigned long cec_xfer_start_jiffies; u8 cec_output2bus_map[MAX_OUTPUTS]; + struct task_struct *kthread_cec; + wait_queue_head_t kthread_waitq_cec; + struct vivid_cec_xfer xfers[MAX_OUTPUTS]; + spinlock_t cec_xfers_slock; /* read and write cec messages */ + u32 cec_sft; /* bus signal free time, in bit periods */ + u8 last_initiator; /* CEC OSD String */ char osd[14];
Currently, the vivid emulation of cec message transmission does not force adapters to wait until the cec bus has been signal-free for a certain number of bit periods before transmitting or re-transmitting a message. Without enforcing the signal-free time requirements, adapters do not share the bus very well and some messages are sent too quickly while other messages are lost. By emulating a signal-free time and forcing adapters to wait their turn to transmit, the vivid emulation of cec transmission is much more reliable. Signed-off-by: Deborah Brouwer <deborahbrouwer3563@gmail.com> --- Changes since v1: - use actual message length instead of max when copying - check for kthread_stop() within bus - store the last_initiator in the vivid state - update the last_initiator as soon as it is known and adjust sfts - use last_initiator to assign sft when transmit is called - use function for division drivers/media/test-drivers/vivid/vivid-cec.c | 341 ++++++++++-------- drivers/media/test-drivers/vivid/vivid-cec.h | 9 +- drivers/media/test-drivers/vivid/vivid-core.c | 37 +- drivers/media/test-drivers/vivid/vivid-core.h | 23 +- 4 files changed, 218 insertions(+), 192 deletions(-)