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

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commit f23c52aafb1675ab1d1f46914556d8e29cbbf7b3 upstream.

Commit 7a637784d5 ("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: 7a637784d5 ("serial: imx: reduce RX interrupt frequency")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20250619114617.2791939-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Fabio Estevam
2025-06-19 08:46:17 -03:00
committed by Greg Kroah-Hartman
parent 40f62f8cf8
commit f90d78d65c
1 changed files with 12 additions and 5 deletions
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17
drivers/tty/serial/imx.c
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@@ -234,6 +234,7 @@ 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 {
@@ -1337,6 +1338,7 @@ 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 */
@@ -1449,7 +1451,7 @@ 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;
}
@@ -1474,7 +1476,12 @@ 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
@@ -1887,7 +1894,7 @@ 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);
spin_lock_irqsave(&sport->port.lock, flags);
@@ -1979,7 +1986,7 @@ 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);
}
@@ -2164,7 +2171,7 @@ 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);