From patchwork Tue Sep 20 23:35:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 607916 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 90E27C6FA82 for ; Tue, 20 Sep 2022 23:42:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231618AbiITXmi (ORCPT ); Tue, 20 Sep 2022 19:42:38 -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-serial@vger.kernel.org A SERIAL_8250_16550A_VARIANTS configuration option has been recently defined that lets one request the 8250 driver not to probe for 16550A device features so as to reduce the driver's device startup time in virtual machines. Some actual hardware devices require these features to have been fully determined however for their driver to work correctly, so define a flag to let drivers request full 16550A feature probing on a device-by-device basis if required regardless of the SERIAL_8250_16550A_VARIANTS option 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 =================================================================== --- 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 = PORT_16550A; up->capabilities |= UART_CAP_FIFO; - if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS)) + if (!IS_ENABLED(CONFIG_SERIAL_8250_16550A_VARIANTS) && + !(up->port.flags & UPF_FULL_PROBE)) return; /* Index: linux-macro/include/linux/serial_core.h =================================================================== --- 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; }; -typedef unsigned int __bitwise upf_t; +typedef u64 __bitwise upf_t; typedef unsigned int __bitwise upstat_t; 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)) #define __UPF_CHANGE_MASK 0x17fff #define UPF_CHANGE_MASK ((__force upf_t) __UPF_CHANGE_MASK)