From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Richard W.M. Jones" Subject: [PATCH] 8250: Hypervisors always export working 16550A UARTs. Date: Thu, 28 Apr 2016 23:18:33 +0100 Message-ID: <1461881913-23967-2-git-send-email-rjones@redhat.com> References: <1461881913-23967-1-git-send-email-rjones@redhat.com> Return-path: In-Reply-To: <1461881913-23967-1-git-send-email-rjones@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: gregkh@linuxfoundation.org Cc: jslaby@suse.com, peter@hurleysoftware.com, andriy.shevchenko@linux.intel.com, phillip.raffeck@fau.de, anton.wuerfel@fau.de, yamada.masahiro@socionext.com, matwey@sai.msu.ru, valentinrothberg@gmail.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, ddutile@redhat.com List-Id: linux-serial@vger.kernel.org Currently autoconf spends 25ms (on my laptop) testing if the UART exported to it by KVM is an 8250 without FIFO and/or with strange quirks, which it obviously isn't. Assume it is exported to us by a hypervisor, it's a normal, working 16550A. Signed-off-by: Richard W.M. Jones --- drivers/tty/serial/8250/8250_port.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 00ad2637..de19924 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1171,6 +1171,13 @@ static void autoconfig(struct uart_8250_port *up) if (!port->iobase && !port->mapbase && !port->membase) return; + /* Hypervisors always export working 16550A devices. */ + if (cpu_has_hypervisor) { + up->port.type = PORT_16550A; + up->capabilities |= UART_CAP_FIFO; + return; + } + DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04lx, 0x%p): ", serial_index(port), port->iobase, port->membase); -- 2.7.4