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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 B0160C433FF for ; Wed, 31 Jul 2019 17:31:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 851F6214DA for ; Wed, 31 Jul 2019 17:31:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BlrDk3S9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730768AbfGaRbm (ORCPT ); Wed, 31 Jul 2019 13:31:42 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:44102 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730740AbfGaRbh (ORCPT ); Wed, 31 Jul 2019 13:31:37 -0400 Received: by mail-pg1-f194.google.com with SMTP id i18so32383702pgl.11; Wed, 31 Jul 2019 10:31:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=qV6Busv6K6PZcOPCNp9BVszEaNH5iQz+7fpeXLC5Mlw=; b=BlrDk3S9CzohBJMWhD4N1C5ISGUaJMH3qZBuh4ClRHvjooDE87Io+uU3De7AY9Gy8K 037vTg2QkUyjV6ftnL+UZ+QyY+E/5mlYTxETZ80D9bMd6GEn3HwXT9av1Vzj3bBxnQ0M sToHZmgmgx6BaXw2LEE98uSarHlvSB4PPMdecFiafQYdS/Y4MfbiKxamyuiN2ipqXB3c oTHbTNajX2UGZ9g0zODii5lGSxigkJz9Kx015cwUsF1Z4H31WvElCVwCHAGwA3BBgohR gvQUsdsyql6Cxeji2XZOuX2Crns4rnOHeVkn7pPsPZq4Fe8GyJhdivXVsKckLXG3MQ5B o4IQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=qV6Busv6K6PZcOPCNp9BVszEaNH5iQz+7fpeXLC5Mlw=; b=miBx60hS5mR0CvI+c/rT7CzahY9Nd6P7jOdr2dfGW3rm6usAoshREwe6m98LjWI+o2 XIP0pUPmt3M71S4UouAtiI+b4u/pwPPwT512GdAOA9GmAEjyIUh0MENLmIKO9Y1DUczF DAH4Nl24XaC4a36w/HAH6JjOnGxiK2z+APl8x1GgHZMBLOd4EYFhD6wVofvNU22KFq8e wTtdbcfAshTD1Bmu25HdO6HtM8az7pxMiBoBDMVnKhwzuVCxuzdG4x17t80N3HM+rEj4 1319PcE7raF9h/6b/cekBbTcEjoB121B2+nCJs0uaHTRHJOEJOMWJLAZpGfZXBYgIy4N 6p4w== X-Gm-Message-State: APjAAAVQhYWR4i7fJKMlRkubkQbDaWb69T92kEQtMVWvGPJXQsW7Vcn+ Cv6opywQt852WvnfeEy/2Tg5THvmNzs= X-Google-Smtp-Source: APXvYqwpKDngBhEeRb7Atr0Q/m65KimWIhobbvb859KvmFlySjMQGiN6LaJPKw2392Ldjdu3Rl7/zg== X-Received: by 2002:aa7:9531:: with SMTP id c17mr50336275pfp.130.1564594296678; Wed, 31 Jul 2019 10:31:36 -0700 (PDT) Received: from localhost.localdomain ([2607:fb90:4ad:5a0b:2aff:6e0f:8973:5a26]) by smtp.gmail.com with ESMTPSA id bo20sm2089617pjb.23.2019.07.31.10.31.34 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 31 Jul 2019 10:31:36 -0700 (PDT) From: Andrey Smirnov To: linux-serial@vger.kernel.org Cc: Andrey Smirnov , Stefan Agner , Chris Healy , Cory Tusar , Lucas Stach , Greg Kroah-Hartman , Jiri Slaby , linux-imx@nxp.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 14/23] tty: serial: fsl_lpuart: Use cpu_relax() instead of barrier() Date: Wed, 31 Jul 2019 10:30:36 -0700 Message-Id: <20190731173045.11718-15-andrew.smirnov@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190731173045.11718-1-andrew.smirnov@gmail.com> References: <20190731173045.11718-1-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use cpu_relax() instead of barrier() in a tight polling loops to make them a bit more idiomatic. Should also improve things on ARM64 a bit since cpu_relax() will expand into "yield" instruction there. Signed-off-by: Andrey Smirnov Cc: Stefan Agner Cc: Chris Healy Cc: Cory Tusar Cc: Lucas Stach Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linux-imx@nxp.com Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- drivers/tty/serial/fsl_lpuart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index eb748ef85da7..58043e01a242 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -553,14 +553,14 @@ static void lpuart_wait_bit_set(struct uart_port *port, unsigned int offset, u8 bit) { while (!(readb(port->membase + offset) & bit)) - barrier(); + cpu_relax(); } static void lpuart32_wait_bit_set(struct uart_port *port, unsigned int offset, u32 bit) { while (!(lpuart32_read(port, offset) & bit)) - barrier(); + cpu_relax(); } #if defined(CONFIG_CONSOLE_POLL) -- 2.21.0