Messages in this thread Patch in this message | | | From | Matthias Schiffer <> | Subject | [PATCH] serial: imx: Raise TX trigger level to 8 | Date | Wed, 8 May 2024 15:37:44 +0200 |
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At the default TX trigger level of 2 in non-DMA mode (meaning that an interrupt is generated when less than 2 characters are left in the FIFO), we have observed frequent buffer underruns at 115200 Baud on an i.MX8M Nano. This can cause communication issues if the receiving side expects a continuous transfer.
Increasing the level to 8 makes the UART trigger an interrupt earlier, giving the kernel enough time to refill the FIFO, at the cost of triggering one interrupt per ~24 instead of ~30 bytes of transmitted data (as the i.MX UART has a 32 byte FIFO).
Signed-off-by: Michael Krummsdorf <michael.krummsdorf@tq-group.com> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> --- drivers/tty/serial/imx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 79f1503cd75b4..2eb22594960f3 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1305,7 +1305,7 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport) } -#define TXTL_DEFAULT 2 /* reset default */ +#define TXTL_DEFAULT 8 #define RXTL_DEFAULT 8 /* 8 characters or aging timer */ #define TXTL_DMA 8 /* DMA burst setting */ #define RXTL_DMA 9 /* DMA burst setting */ -- TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht München, HRB 105018 Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider https://www.tq-group.com/
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