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serial: imx: get rid of unbounded busy-waiting loop 

imx_set_termios(): remove busy-waiting "drain Tx FIFO" loop. Worse
yet, it was potentially unbounded wait due to RTS/CTS (hardware)
handshake.

Let user space ensure draining is done before termios change, if
draining is needed in the first place.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-2-git-send-email-sorganov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Sergey Organov 2019-08-28 21:37:51 +03:00 committed by Greg Kroah-Hartman
parent 8016c3da0c
commit 2eda5345e4
1 changed files with 1 additions and 4 deletions
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5
drivers/tty/serial/imx.c
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@ -1644,7 +1644,7 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
uart_update_timeout(port, termios->c_cflag, baud);
/*
* disable interrupts and drain transmitter
* disable interrupts
*/
old_ucr1 = imx_uart_readl(sport, UCR1);
imx_uart_writel(sport,
@ -1652,9 +1652,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
UCR1);
imx_uart_writel(sport, old_ucr2 & ~UCR2_ATEN, UCR2);
while (!(imx_uart_readl(sport, USR2) & USR2_TXDC))
barrier();
/* then, disable everything */
imx_uart_writel(sport, old_ucr2 & ~(UCR2_TXEN | UCR2_RXEN | UCR2_ATEN), UCR2);