4.16-stable review patch. If anyone has any objections, please let me know.
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From: Gabriel Matni gabriel.matni@exfo.com
[ Upstream commit c685af1108d7c303f0b901413405d68eaeac4477 ]
Fixes missing characters on kernel console at low baud rates (i.e.9600). The driver should poll TX_RDY or TX_FIFO_EMP instead of TX_EMP to ensure that the transmitter holding register (THR) is ready to receive a new byte.
TX_EMP tells us when it is possible to send a break sequence via SND_BRK_SEQ. While this also indicates that both the THR and the TSR are empty, it does not guarantee that a new byte can be written just yet.
Fixes: 30530791a7a0 ("serial: mvebu-uart: initial support for Armada-3700 serial port") Reviewed-by: Miquel Raynal miquel.raynal@bootlin.com Acked-by: Gregory CLEMENT gregory.clement@bootlin.com Signed-off-by: Gabriel Matni gabriel.matni@exfo.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/mvebu-uart.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -617,7 +617,7 @@ static void wait_for_xmitr(struct uart_p u32 val;
readl_poll_timeout_atomic(port->membase + UART_STAT, val, - (val & STAT_TX_EMP), 1, 10000); + (val & STAT_TX_RDY(port)), 1, 10000); }
static void mvebu_uart_console_putchar(struct uart_port *port, int ch)