From nobody Thu Apr 2 21:53:37 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B716C54EE9 for ; Tue, 20 Sep 2022 23:42:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231633AbiITXmk (ORCPT ); Tue, 20 Sep 2022 19:42:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231489AbiITXmU (ORCPT ); Tue, 20 Sep 2022 19:42:20 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [78.133.224.34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EF6957656; Tue, 20 Sep 2022 16:40:33 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id B999592009D; Wed, 21 Sep 2022 01:35:32 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id B291F92009B; Wed, 21 Sep 2022 00:35:32 +0100 (BST) Date: Wed, 21 Sep 2022 00:35:32 +0100 (BST) From: "Maciej W. Rozycki" To: Greg Kroah-Hartman , Jiri Slaby cc: Josh Triplett , Anders Blomdell , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2 1/3] serial: 8250: Let drivers request full 16550A feature probing In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A SERIAL_8250_16550A_VARIANTS configuration option has been recently=20 defined that lets one request the 8250 driver not to probe for 16550A=20 device features so as to reduce the driver's device startup time in=20 virtual machines. Some actual hardware devices require these features to have been fully=20 determined however for their driver to work correctly, so define a flag=20 to let drivers request full 16550A feature probing on a device-by-device=20 basis if required regardless of the SERIAL_8250_16550A_VARIANTS option=20 setting chosen. Signed-off-by: Maciej W. Rozycki Reported-by: Anders Blomdell Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes = of 16550A variants") Cc: stable@vger.kernel.org # v5.6+ --- Changes from v1: - Use `u64' rather than `__u64' as the data type. --- drivers/tty/serial/8250/8250_port.c | 3 ++- include/linux/serial_core.h | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) linux-serial-8250-full-probe.diff Index: linux-macro/drivers/tty/serial/8250/8250_port.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-macro.orig/drivers/tty/serial/8250/8250_port.c +++ linux-macro/drivers/tty/serial/8250/8250_port.c @@ -1021,7 +1021,8 @@ static void autoconfig_16550a(struct uar up->port.type =3D PORT_16550A; up->capabilities |=3D UART_CAP_FIFO; =20 - if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS)) + if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS) && + !(up->port.flags & UPF_FULL_PROBE)) return; =20 /* Index: linux-macro/include/linux/serial_core.h =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-macro.orig/include/linux/serial_core.h +++ linux-macro/include/linux/serial_core.h @@ -414,7 +414,7 @@ struct uart_icount { __u32 buf_overrun; }; =20 -typedef unsigned int __bitwise upf_t; +typedef u64 __bitwise upf_t; typedef unsigned int __bitwise upstat_t; =20 struct uart_port { @@ -522,6 +522,7 @@ struct uart_port { #define UPF_FIXED_PORT ((__force upf_t) (1 << 29)) #define UPF_DEAD ((__force upf_t) (1 << 30)) #define UPF_IOREMAP ((__force upf_t) (1 << 31)) +#define UPF_FULL_PROBE ((__force upf_t) (1ULL << 32)) =20 #define __UPF_CHANGE_MASK 0x17fff #define UPF_CHANGE_MASK ((__force upf_t) __UPF_CHANGE_MASK)