Commit f23c52aa authored by Fabio Estevam's avatar Fabio Estevam Committed by Greg Kroah-Hartman
Browse files

serial: imx: Restore original RXTL for console to fix data loss 



Commit 7a637784 ("serial: imx: reduce RX interrupt frequency")
introduced a regression on the i.MX6UL EVK board. The issue can be
reproduced with the following steps:

- Open vi on the board.
- Paste a text file (~150 characters).
- Save the file, then repeat the process.
- Compare the sha256sum of the saved files.

The checksums do not match due to missing characters or entire lines.

Fix this by restoring the RXTL value to 1 when the UART is used as a
console.

This ensures timely RX interrupts and reliable data reception in console
mode.

With this change, pasted content is saved correctly, and checksums are
always consistent.

Cc: stable <stable@kernel.org>
Fixes: 7a637784 ("serial: imx: reduce RX interrupt frequency")
Signed-off-by: default avatarFabio Estevam <festevam@gmail.com>
Reviewed-by: default avatarStefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20250619114617.2791939-1-festevam@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d36f0e9a

drivers/tty/serial/imx.c

+12 −5
Original line number Diff line number Diff line
@@ -235,6 +235,7 @@ struct imx_port { 
	enum imx_tx_state	tx_state;

	struct hrtimer		trigger_start_tx;

	struct hrtimer		trigger_stop_tx;

	unsigned int		rxtl;

};



struct imx_port_ucrs {
@@ -1339,6 +1340,7 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport) 


#define TXTL_DEFAULT 8

#define RXTL_DEFAULT 8 /* 8 characters or aging timer */

#define RXTL_CONSOLE_DEFAULT 1

#define TXTL_DMA 8 /* DMA burst setting */

#define RXTL_DMA 9 /* DMA burst setting */
@@ -1457,7 +1459,7 @@ static void imx_uart_disable_dma(struct imx_port *sport) 
	ucr1 &= ~(UCR1_RXDMAEN | UCR1_TXDMAEN | UCR1_ATDMAEN);

	imx_uart_writel(sport, ucr1, UCR1);



	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);

	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, sport->rxtl);



	sport->dma_is_enabled = 0;

}
@@ -1482,7 +1484,12 @@ static int imx_uart_startup(struct uart_port *port) 
		return retval;

	}



	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);

	if (uart_console(&sport->port))

		sport->rxtl = RXTL_CONSOLE_DEFAULT;

	else

		sport->rxtl = RXTL_DEFAULT;



	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, sport->rxtl);



	/* disable the DREN bit (Data Ready interrupt enable) before

	 * requesting IRQs
@@ -1948,7 +1955,7 @@ static int imx_uart_poll_init(struct uart_port *port) 
	if (retval)

		clk_disable_unprepare(sport->clk_ipg);



	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);

	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, sport->rxtl);



	uart_port_lock_irqsave(&sport->port, &flags);
@@ -2040,7 +2047,7 @@ static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termio 
		/* If the receiver trigger is 0, set it to a default value */

		ufcr = imx_uart_readl(sport, UFCR);

		if ((ufcr & UFCR_RXTL_MASK) == 0)

			imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);

			imx_uart_setup_ufcr(sport, TXTL_DEFAULT, sport->rxtl);

		imx_uart_start_rx(port);

	}
@@ -2302,7 +2309,7 @@ imx_uart_console_setup(struct console *co, char *options) 
	else

		imx_uart_console_get_options(sport, &baud, &parity, &bits);



	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);

	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, sport->rxtl);



	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);