From 57c0741b8c15b93ba4aa92c6618cde6f3f4115b2 Mon Sep 17 00:00:00 2001 From: Fushuai Wang Date: Fri, 24 Jul 2026 17:31:51 +0800 Subject: [PATCH] Revert "serial: 8250: Clear CON_PRINTBUFFER on port re-registration" This reverts commit d338ab1d90603f875c4f7ed223406535378173a5. uart_console() only indicates that the port is selected as the console. It does not mean that the console has already been registered or has printed the buffered messages. On platforms where an initial 8250 port is replaced when the real UART device is registered, clearing CON_PRINTBUFFER causes the console to start at the end of the printk ring buffer. Without earlycon, all messages logged before UART registration are therefore lost. Fixes: d338ab1d9060 ("serial: 8250: Clear CON_PRINTBUFFER on port re-registration") Reported-by: Mark Brown Reported-by: Anirudh Srinivasan Link: https://lore.kernel.org/all/20260522101042.21976-1-fushuai.wang@linux.dev/ Signed-off-by: Fushuai Wang Reviewed-by: John Ogness Link: https://patch.msgid.link/20260724093151.53216-1-fushuai.wang@linux.dev Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_core.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index c0e8a4efbdcc..f49862d90eeb 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -720,12 +720,8 @@ int serial8250_register_8250_port(const struct uart_8250_port *up) /* Preserve specified console flow control. */ cons_flow = uart_cons_flow_enabled(&uart->port); - if (uart->port.dev) { - if (uart_console(&uart->port)) - uart->port.cons->flags &= ~CON_PRINTBUFFER; - + if (uart->port.dev) uart_remove_one_port(&serial8250_reg, &uart->port); - } uart->port.ctrl_id = up->port.ctrl_id; uart->port.port_id = up->port.port_id;