From nobody Fri Oct 17 10:31:39 2025 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 50014C43219 for ; Wed, 19 Oct 2022 13:52:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233726AbiJSNwe (ORCPT ); Wed, 19 Oct 2022 09:52:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231347AbiJSNv7 (ORCPT ); Wed, 19 Oct 2022 09:51:59 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6C95106930; Wed, 19 Oct 2022 06:35:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 3BE99CE20ED; Wed, 19 Oct 2022 08:41:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A13FC433D6; Wed, 19 Oct 2022 08:41:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666168907; bh=KM5aJ8W23YxmKOBqyJnPA3XBpiJZ3LNYv8qiLaoe1eM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PrcnaS1ITy2q32Jr8ey9mH7zDRuZb3tU//5Za3LtbpUd+bn7U2DOvtuZLCFu/dUD+ 0+qJdTwOcb3w8co7N7N6koumnrob4X1lilTzBzQ8fgFhVnjWSj+Sl6f3sVt7/kCHfh 5eWyWwXCZ2T9m+s3JbdHMekomIUDyaM54ugR4Uy8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anders Blomdell , "Maciej W. Rozycki" Subject: [PATCH 6.0 094/862] serial: 8250: Let drivers request full 16550A feature probing Date: Wed, 19 Oct 2022 10:23:01 +0200 Message-Id: <20221019083254.093554124@linuxfoundation.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221019083249.951566199@linuxfoundation.org> References: <20221019083249.951566199@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Maciej W. Rozycki commit 9906890c89e4dbd900ed87ad3040080339a7f411 upstream. 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. Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes = of 16550A variants") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Anders Blomdell Signed-off-by: Maciej W. Rozycki Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209202357520.41633@angie.o= rcam.me.uk Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 3 ++- include/linux/serial_core.h | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1023,7 +1023,8 @@ 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 /* --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -422,7 +422,7 @@ 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 { @@ -530,6 +530,7 @@ 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)