diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/sc16is7xx.c | 38 |
1 files changed, 30 insertions, 8 deletions
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index fa7805d2c..1f7e98c2b 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -216,6 +216,8 @@ #define SC16IS7XX_TLR_TX_TRIGGER(words) ((((words) / 4) & 0x0f) << 0) #define SC16IS7XX_TLR_RX_TRIGGER(words) ((((words) / 4) & 0x0f) << 4) +#define SC16IS7XX_TX_TRIGGER_LEVEL 8 + /* IOControl register bits (Only 75x/76x) */ #define SC16IS7XX_IOCONTROL_LATCH_BIT BIT(0) /* Enable input latching */ #define SC16IS7XX_IOCONTROL_MODEM_A_BIT BIT(1) /* Enable GPIO[7:4] as modem A pins */ @@ -647,6 +649,21 @@ static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen, tty_flip_buffer_push(&port->state->port); } +static unsigned int sc16is7xx_txlvl(struct uart_port *port) +{ + unsigned int txlvl; + + txlvl = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG); + if (txlvl > SC16IS7XX_FIFO_SIZE) { + dev_err_ratelimited(port->dev, + "chip reports %u free bytes in TX FIFO, but it only has %u\n", + txlvl, SC16IS7XX_FIFO_SIZE); + return 0; + } + + return txlvl; +} + static void sc16is7xx_handle_tx(struct uart_port *port) { struct tty_port *tport = &port->state->port; @@ -668,13 +685,7 @@ static void sc16is7xx_handle_tx(struct uart_port *port) } /* Limit to space available in TX FIFO */ - txlen = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG); - if (txlen > SC16IS7XX_FIFO_SIZE) { - dev_err_ratelimited(port->dev, - "chip reports %d free bytes in TX fifo, but it only has %d", - txlen, SC16IS7XX_FIFO_SIZE); - txlen = 0; - } + txlen = sc16is7xx_txlvl(port); /* Handle circular buffer wrap-around by sending multiple segments */ while (txlen > 0 && !kfifo_is_empty(&tport->xmit_fifo)) { @@ -687,7 +698,14 @@ static void sc16is7xx_handle_tx(struct uart_port *port) sc16is7xx_fifo_write(port, tail, to_send); uart_xmit_advance(port, to_send); - txlen -= to_send; + + if (kfifo_is_empty(&tport->xmit_fifo)) + break; + + /* Refill below the trigger to enable the next THRI crossing. */ + txlen = sc16is7xx_txlvl(port); + if (txlen < SC16IS7XX_TX_TRIGGER_LEVEL) + break; } uart_port_lock_irqsave(port, &flags); @@ -1139,6 +1157,10 @@ static int sc16is7xx_startup(struct uart_port *port) SC16IS7XX_TCR_RX_RESUME(24) | SC16IS7XX_TCR_RX_HALT(48)); + /* Sync hardware and software TX trigger levels */ + sc16is7xx_port_write(port, SC16IS7XX_TLR_REG, + SC16IS7XX_TLR_TX_TRIGGER(SC16IS7XX_TX_TRIGGER_LEVEL)); + /* Disable TCR/TLR access */ sc16is7xx_port_update(port, SC16IS7XX_MCR_REG, SC16IS7XX_MCR_TCRTLR_BIT, 0); |