diff options
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 3d569cd68f5..b69356c227c 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1654,13 +1654,26 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, old_cr &= ~ST_UART011_CR_OVSFACT; } + /* + * Workaround for the ST Micro oversampling variants to + * increase the bitrate slightly, by lowering the divisor, + * to avoid delayed sampling of start bit at high speeds, + * else we see data corruption. + */ + if (uap->vendor->oversampling) { + if ((baud >= 3000000) && (baud < 3250000) && (quot > 1)) + quot -= 1; + else if ((baud > 3250000) && (quot > 2)) + quot -= 2; + } /* Set baud rate */ writew(quot & 0x3f, port->membase + UART011_FBRD); writew(quot >> 6, port->membase + UART011_IBRD); /* * ----------v----------v----------v----------v----- - * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L + * NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER + * UART011_FBRD & UART011_IBRD. * ----------^----------^----------^----------^----- */ writew(lcr_h, port->membase + uap->lcrh_rx); |