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 X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBC6DC433DF for ; Mon, 6 Jul 2020 11:31:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF6E62073E for ; Mon, 6 Jul 2020 11:31:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="do98fXC1"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="e02smifr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729005AbgGFLbR (ORCPT ); Mon, 6 Jul 2020 07:31:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728859AbgGFLbR (ORCPT ); Mon, 6 Jul 2020 07:31:17 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC39BC061794 for ; Mon, 6 Jul 2020 04:31:16 -0700 (PDT) From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1594035075; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=zIjr59zT/ebHtB1OersU4qLeRIoOyUYlrI9yu0DaPO0=; b=do98fXC1FGkK0E7Fn2LbBXk/QTKlQVhmeQuF59Ki8hZOR3/Ci2hDkKEInuRYu5T4SfPnFo J88n+fIcn00/3PpiBGZZbNrHPijv/rgTceVxJY/YAB1Jm8lf166G3JMmgWv455lYsu3gXe WahJjVbkyC1xdBxf6GuWmhBqZ1TYHIB3pyNX/L4/u4MZi2psXMt3bsezSJKcrVwIrCirLT hJcVivYW5KtOAcSKhDiuRBBp14wLE2FmQmmEJZRIzxSltROcVyR2ylGAweopVuJufdxxDV wfVhxy3sSLsBXicEujJpVtJGsiJE1gLVn8LmfS7Xi/TRg95sJ9iIquRhauBPiw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1594035075; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=zIjr59zT/ebHtB1OersU4qLeRIoOyUYlrI9yu0DaPO0=; b=e02smifr93XZX3Wn5TwGUzMVRAp6tsngVXmHDmLZlWgIZTFIQmyRpjSfiB1rfv8E7Jr4CE uSd53rEr/P2jc5BQ== To: Andy Shevchenko , Sergey Senozhatsky Cc: Tony Lindgren , Petr Mladek , Raul Rangel , Sergey Senozhatsky , linux-kernel , Greg Kroah-Hartman , Andy Shevchenko , "S\, Shirish" , Peter Zijlstra , John Ogness , Steven Rostedt Subject: Re: UART/TTY console deadlock In-Reply-To: References: <20200630035816.GA21591@jagdpanzerIV.localdomain> <20200630102141.GA11587@alley> <20200630105512.GA530@jagdpanzerIV.localdomain> <20200630122239.GD6173@alley> <20200630130534.GB145027@jagdpanzerIV.localdomain> <20200630180255.GD37466@atomide.com> <20200702051213.GB3450@jagdpanzerIV.localdomain> <20200702160514.GK37466@atomide.com> <20200703103241.GB182102@jagdpanzerIV.localdomain> Date: Mon, 06 Jul 2020 13:31:01 +0200 Message-ID: <877dvg6ft6.fsf@kurt> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Hi, On Sat Jul 04 2020, Andy Shevchenko wrote: > On Fri, Jul 3, 2020 at 1:32 PM Sergey Senozhatsky > wrote: >> >> On (20/07/02 09:05), Tony Lindgren wrote: >> > * Sergey Senozhatsky [200702 05:13]: >> > > On (20/06/30 11:02), Tony Lindgren wrote: >> > > > This conditional disable for irq_shared does not look nice to me >> > > > from the other device point of view :) >> > > > >> > > > Would it be possible to just set up te dummy interrupt handler >> > > > for the startup, then change it back afterwards? See for example >> > > > omap8250_no_handle_irq(). >> > > >> > > I think we can do it. serial8250_do_startup() and irq handler take >> > > port->lock, so they should be synchronized. >> > > >> > > Something like this then? >> > >> > Yeah thanks this should work better for shared irq. >> >> This is, basically, an equivalent of >> >> --- >> drivers/tty/serial/8250/8250_port.c | 5 +---- >> 1 file changed, 1 insertion(+), 4 deletions(-) >> >> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c >> index d64ca77d9cfa..dba7747d2ddd 100644 >> --- a/drivers/tty/serial/8250/8250_port.c >> +++ b/drivers/tty/serial/8250/8250_port.c >> @@ -2275,6 +2275,7 @@ int serial8250_do_startup(struct uart_port *port) >> >> if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { >> unsigned char iir1; >> + >> /* >> * Test for UARTs that do not reassert THRE when the >> * transmitter is idle and the interrupt has already >> @@ -2284,8 +2285,6 @@ int serial8250_do_startup(struct uart_port *port) >> * allow register changes to become visible. >> */ >> spin_lock_irqsave(&port->lock, flags); >> - if (up->port.irqflags & IRQF_SHARED) >> - disable_irq_nosync(port->irq); >> >> wait_for_xmitr(up, UART_LSR_THRE); >> serial_port_out_sync(port, UART_IER, UART_IER_THRI); >> @@ -2297,8 +2296,6 @@ int serial8250_do_startup(struct uart_port *port) >> iir = serial_port_in(port, UART_IIR); >> serial_port_out(port, UART_IER, 0); >> >> - if (port->irqflags & IRQF_SHARED) >> - enable_irq(port->irq); >> spin_unlock_irqrestore(&port->lock, flags); >> >> /* > > ...which effectively is a revert of > > 768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and > RT kernels") Please, don't revert that commit. I've faced the same issue as described in the commit log. There is hardware available with shared UART interrupt lines. 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