Commit 197eb5c4 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by Greg Kroah-Hartman
Browse files

serial: 8250_dw: Use serial_lsr_in() in dw8250_handle_irq() 



dw8250_handle_irq() reads LSR under a few conditions, convert both to
use serial_lsr_in() in order to preserve LSR flags properly across
reads.

Fixes: 424d7918 ("serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt")
Fixes: aa63d786 ("serial: 8250: dw: Add support for DMA flow controlling devices")
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220608095431.18376-6-ilpo.jarvinen@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7a3525e4

drivers/tty/serial/8250/8250_dw.c

+2 −2
Original line number Diff line number Diff line
@@ -253,7 +253,7 @@ static int dw8250_handle_irq(struct uart_port *p) 
	 */

	if (!up->dma && rx_timeout) {

		spin_lock_irqsave(&p->lock, flags);

		status = p->serial_in(p, UART_LSR);

		status = serial_lsr_in(up);



		if (!(status & (UART_LSR_DR | UART_LSR_BI)))

			(void) p->serial_in(p, UART_RX);
@@ -263,7 +263,7 @@ static int dw8250_handle_irq(struct uart_port *p) 


	/* Manually stop the Rx DMA transfer when acting as flow controller */

	if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) {

		status = p->serial_in(p, UART_LSR);

		status = serial_lsr_in(up);

		if (status & (UART_LSR_DR | UART_LSR_BI)) {

			dw8250_writel_ext(p, RZN1_UART_RDMACR, 0);

			dw8250_writel_ext(p, DW_UART_DMASA, 1);