~ruther/qmk_firmware

881aab9e76d4cab5b1c58548cb47ff4a2c8868cb — Stefan Kerkmann 3 years ago ea90fcc
Stabilize Half-duplex PIO split comms take 2 (#18421)

...by moving the actually timing critical `enter_rx_state()` and
`leave_rx_state()` functions to RAM in order to not be affected by XIP
cache spikes. This commit also reverts the hacky USB interrupt disabling
that was done in 293c53d774
1 files changed, 2 insertions(+), 15 deletions(-)

M platforms/chibios/drivers/vendor/RP/RP2040/serial_vendor.c
M platforms/chibios/drivers/vendor/RP/RP2040/serial_vendor.c => platforms/chibios/drivers/vendor/RP/RP2040/serial_vendor.c +2 -15
@@ 140,9 140,8 @@ void pio_serve_interrupt(void) {
// strength is chosen because the transmitting side must still be able to drive
// the signal low. With this configuration the rise times are fast enough and
// the generated low level with 360mV will generate a logical zero.
static inline void enter_rx_state(void) {
static void __no_inline_not_in_flash_func(enter_rx_state)(void) {
    osalSysLock();
    nvicEnableVector(RP_USBCTRL_IRQ_NUMBER, RP_IRQ_USB0_PRIORITY);
    // Wait for the transmitting state machines FIFO to run empty. At this point
    // the last byte has been pulled from the transmitting state machines FIFO
    // into the output shift register. We have to wait a tiny bit more until


@@ 162,11 161,8 @@ static inline void enter_rx_state(void) {
    osalSysUnlock();
}

static inline void leave_rx_state(void) {
static void __no_inline_not_in_flash_func(leave_rx_state)(void) {
    osalSysLock();
    // We don't want to be interrupted by frequent (1KHz) USB interrupts while
    // doing our timing critical sending operation.
    nvicDisableVector(RP_USBCTRL_IRQ_NUMBER);
    // In Half-duplex operation the tx pin dual-functions as sender and
    // receiver. To not receive the data we will send, we disable the receiving
    // state machine.


@@ 198,11 194,6 @@ static inline msg_t sync_tx(sysinterval_t timeout) {
    msg_t msg = MSG_OK;
    osalSysLock();
    while (pio_sm_is_tx_fifo_full(pio, tx_state_machine)) {
#if !defined(SERIAL_USART_FULL_DUPLEX)
        // Enable USB interrupts again, because we might sleep for a long time
        // here and don't want to be disconnected from the host.
        nvicEnableVector(RP_USBCTRL_IRQ_NUMBER, RP_IRQ_USB0_PRIORITY);
#endif
        pio_set_irq0_source_enabled(pio, pis_sm0_tx_fifo_not_full + tx_state_machine, true);
        msg = osalThreadSuspendTimeoutS(&tx_thread, timeout);
        if (msg < MSG_OK) {


@@ 210,10 201,6 @@ static inline msg_t sync_tx(sysinterval_t timeout) {
            break;
        }
    }
#if !defined(SERIAL_USART_FULL_DUPLEX)
    // Entering timing critical territory again.
    nvicDisableVector(RP_USBCTRL_IRQ_NUMBER);
#endif
    osalSysUnlock();
    return msg;
}