6.15-stable review patch. If anyone has any objections, please let me know.
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From: Fabio Estevam festevam@gmail.com
commit f23c52aafb1675ab1d1f46914556d8e29cbbf7b3 upstream.
Commit 7a637784d517 ("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: 7a637784d517 ("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 --- drivers/tty/serial/imx.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
--- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -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(str
#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 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_ 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 uar 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 /* 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 *c 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);