From 60a9d8d2fc9c4a524c7342499580a88aaa3a2b55 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Marek=20Marczykowski-G=C3=B3recki?= Date: Mon, 16 Aug 2021 15:14:37 +0200 Subject: [PATCH] ns16550: do not override fifo size if explicitly set MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit If fifo size is already set via uart_params, do not force it to 16 - which may not match the actual hardware. Specifically Exar cards have fifo of 256 bytes. Signed-off-by: Marek Marczykowski-Górecki Reviewed-by: Jan Beulich --- xen/drivers/char/ns16550.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c index 16a73d0c0e..97b85b0225 100644 --- a/xen/drivers/char/ns16550.c +++ b/xen/drivers/char/ns16550.c @@ -357,7 +357,8 @@ static void __init ns16550_init_preirq(struct serial_port *port) ns16550_setup_preirq(uart); /* Check this really is a 16550+. Otherwise we have no FIFOs. */ - if ( ((ns_read_reg(uart, UART_IIR) & 0xc0) == 0xc0) && + if ( uart->fifo_size <= 1 && + ((ns_read_reg(uart, UART_IIR) & 0xc0) == 0xc0) && ((ns_read_reg(uart, UART_FCR) & UART_FCR_TRG14) == UART_FCR_TRG14) ) uart->fifo_size = 16; } -- 2.30.2