diff options
| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2016-08-17 19:20:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-31 17:13:29 +0300 |
| commit | 68af490b03b40cc31b2cd47899661d87ab9f127d (patch) | |
| tree | 987478883148a182b4b80b9d353d0ad9f59608d1 /drivers/tty | |
| parent | d1834babe42246bf0bd0989b8bb19c9807851527 (diff) | |
| download | linux-68af490b03b40cc31b2cd47899661d87ab9f127d.tar.xz | |
serial: 8250: enable AFE on ports where FIFO is 16 bytes
Intel Quark has 16550A compatible UART with autoflow feature enabled. It has
only 16 bytes of FIFO. Currently serial8250_do_set_termios() prevents to enable
autoflow since the minimum requirement of 32 bytes of FIFO size.
Drop a FIFO size limitation to allow autoflow control be enabled on such UARTs.
While here, comment out UART_CAP_AFE for PORT_AR7 since it wasn't working and
it will be not a good idea to use it in conjunction with trigger level of 1
byte.
Suggested-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index c45c1e3f3631..1bd7ea0aff03 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -178,7 +178,7 @@ static const struct serial8250_config uart_config[] = { .fifo_size = 16, .tx_loadsz = 16, .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_00, - .flags = UART_CAP_FIFO | UART_CAP_AFE, + .flags = UART_CAP_FIFO /* | UART_CAP_AFE */, }, [PORT_U6_16550A] = { .name = "U6_16550A", @@ -2549,12 +2549,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, /* * MCR-based auto flow control. When AFE is enabled, RTS will be * deasserted when the receive FIFO contains more characters than - * the trigger, or the MCR RTS bit is cleared. In the case where - * the remote UART is not using CTS auto flow control, we must - * have sufficient FIFO entries for the latency of the remote - * UART to respond. IOW, at least 32 bytes of FIFO. + * the trigger, or the MCR RTS bit is cleared. */ - if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) { + if (up->capabilities & UART_CAP_AFE) { up->mcr &= ~UART_MCR_AFE; if (termios->c_cflag & CRTSCTS) up->mcr |= UART_MCR_AFE; |