From mboxrd@z Thu Jan 1 00:00:00 1970 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 23CA8C433F5 for ; Tue, 4 Jan 2022 07:17:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233104AbiADHR6 (ORCPT ); Tue, 4 Jan 2022 02:17:58 -0500 Received: from mail-ed1-f46.google.com ([209.85.208.46]:37873 "EHLO mail-ed1-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230349AbiADHR6 (ORCPT ); Tue, 4 Jan 2022 02:17:58 -0500 Received: by mail-ed1-f46.google.com with SMTP id o6so144858442edc.4; Mon, 03 Jan 2022 23:17:57 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=pOAXZ90y+NqNgM4bMsWBaGvAJnnSkQQXCw6loSgl2/0=; b=XYdPiyPhm42BJoz5DA3nMwmgWfa6nsyyb3s6hvozNJ9/hjmr9c84cmcFuV3uSnWEow JnkOT1MkU75P+ZBoVGeqsUNMyS+LIB5NbTFzfXsTkB3tbbrSw8BlFj2F8/T2YbMEHTDe ijwGeqLgTIbwZNkjudxsL5bwG58N0bG9EZy2pE8a82Eaj2wP+Yv7/9zH9RTVRREvWqKk HKtJzorDpWofQ2UEw7qjJcNXubBmkDWZuReZpohHaF3C1dWMUTfAZ8VS1pzv2g8ELs9Y O2UZX0239BvNFX4dI/qvkDh1pMp36zai1OCOSFj+Ju+HhfEKFAWmCdXPoT0Ti+O2Al2I ZOIw== X-Gm-Message-State: AOAM532NyvCdQ5JaWR1DTpA4PwuAc74Q4HHyF1bb3xPupo8PrbnfrpRy WLJuGuHy4kwtvjNB/nb04GY= X-Google-Smtp-Source: ABdhPJxyS+tzswPsc9YapgmN417/e8DdnMTszn/Q2wP39cAGpiC/unR8VNCGRsayLdvZRy6T0izOmQ== X-Received: by 2002:a05:6402:1a4f:: with SMTP id bf15mr48104233edb.260.1641280677169; Mon, 03 Jan 2022 23:17:57 -0800 (PST) Received: from ?IPV6:2a0b:e7c0:0:107::70f? ([2a0b:e7c0:0:107::70f]) by smtp.gmail.com with ESMTPSA id j11sm14371994edv.0.2022.01.03.23.17.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Jan 2022 23:17:56 -0800 (PST) Message-ID: <50ceeac0-adb1-30c1-ecc7-ddd4fb94a99c@kernel.org> Date: Tue, 4 Jan 2022 08:17:55 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2] serial: 8250: Move Alpha-specific quirk out of the core Content-Language: en-US To: Lukas Wunner , Greg Kroah-Hartman Cc: linux-serial@vger.kernel.org, Russell King , Ulrich Teichert , Linus Torvalds , Richard Henderson , Ivan Kokshaysky , Matt Turner , linux-alpha@vger.kernel.org, Lino Sanfilippo , Philipp Rosenberger , John Paul Adrian Glaubitz References: From: Jiri Slaby In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 28. 12. 21, 18:22, Lukas Wunner wrote: > struct uart_8250_port contains mcr_mask and mcr_force members whose > sole purpose is to work around an Alpha-specific quirk. This code > doesn't belong in the core where it is executed by everyone else, > so move it to a proper ->set_mctrl callback which is used on the > affected Alpha machine only. > > The quirk was introduced in January 1995: > https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83 > > The members in struct uart_8250_port were added in 2002: > https://git.kernel.org/history/history/c/4524aad27854 > > The quirk applies to non-PCI Alphas and arch/alpha/Kconfig specifies > "select FORCE_PCI if !ALPHA_JENSEN". So apparently the only affected > machine is the EISA-based Jensen that Linus was working on back then: > https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/ > > Up until now the quirk is not applied unless CONFIG_PCI is disabled. > If users forget to do that or run a generic Alpha kernel, the serial > ports aren't usable on Jensen. Avoid by confining the quirk to > CONFIG_ALPHA_JENSEN instead of !CONFIG_PCI. On generic Alpha kernels, > auto-detect at runtime whether the quirk needs to be applied. > > Signed-off-by: Lukas Wunner > Cc: Russell King > Cc: Ulrich Teichert > Cc: Linus Torvalds > --- > Changes in v2: > * Also apply quirk when running a generic Alpha kernel on a Jensen. > * Fix outdated reference to the quirk in sunsu.c. > > drivers/tty/serial/8250/8250.h | 12 ++---------- > drivers/tty/serial/8250/8250_alpha.c | 21 +++++++++++++++++++++ > drivers/tty/serial/8250/8250_core.c | 9 ++++----- > drivers/tty/serial/8250/8250_port.c | 2 +- > drivers/tty/serial/8250/Makefile | 2 ++ > drivers/tty/serial/sunsu.c | 3 ++- > include/linux/serial_8250.h | 2 -- > 7 files changed, 32 insertions(+), 19 deletions(-) > create mode 100644 drivers/tty/serial/8250/8250_alpha.c > > diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h > index 6473361525d1..db784ace25d8 100644 > --- a/drivers/tty/serial/8250/8250.h > +++ b/drivers/tty/serial/8250/8250.h > @@ -241,16 +241,8 @@ static inline int serial8250_in_MCR(struct uart_8250_port *up) > return mctrl; > } > > -#if defined(__alpha__) && !defined(CONFIG_PCI) > -/* > - * Digital did something really horribly wrong with the OUT1 and OUT2 > - * lines on at least some ALPHA's. The failure mode is that if either > - * is cleared, the machine locks up with endless interrupts. > - */ > -#define ALPHA_KLUDGE_MCR (UART_MCR_OUT2 | UART_MCR_OUT1) > -#else > -#define ALPHA_KLUDGE_MCR 0 > -#endif > +bool alpha_jensen(void); > +void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl); > > #ifdef CONFIG_SERIAL_8250_PNP > int serial8250_pnp_init(void); > diff --git a/drivers/tty/serial/8250/8250_alpha.c b/drivers/tty/serial/8250/8250_alpha.c > new file mode 100644 > index 000000000000..58e70328aa4d > --- /dev/null > +++ b/drivers/tty/serial/8250/8250_alpha.c > @@ -0,0 +1,21 @@ > +// SPDX-License-Identifier: GPL-2.0+ > + > +#include > +#include "8250.h" > + > +bool alpha_jensen(void) > +{ > + return !strcmp(alpha_mv.vector_name, "Jensen"); > +} > + > +void alpha_jensen_set_mctrl(struct uart_port *port, unsigned int mctrl) > +{ > + /* > + * Digital did something really horribly wrong with the OUT1 and OUT2 > + * lines on Alpha Jensen. The failure mode is that if either is > + * cleared, the machine locks up with endless interrupts. > + */ > + mctrl |= TIOCM_OUT1 | TIOCM_OUT2; > + > + serial8250_do_set_mctrl(port, mctrl); > +} > diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > index 1ce193daea7f..01d30f6ed8fb 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -509,11 +509,10 @@ static void __init serial8250_isa_init_ports(void) > > up->ops = &univ8250_driver_ops; > > - /* > - * ALPHA_KLUDGE_MCR needs to be killed. > - */ > - up->mcr_mask = ~ALPHA_KLUDGE_MCR; > - up->mcr_force = ALPHA_KLUDGE_MCR; > + if (IS_ENABLED(CONFIG_ALPHA_JENSEN) || > + (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen())) It'd be definitely nicer, if here was only "if (alpha_jensen())". The rest would be done in the header or in 8250_alpha.c. Or even create an empty __weak arch_serial8250_set_defaults() and also one non-empty in arch/alpha/? thanks, -- js suse labs