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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 C7490C31E40 for ; Fri, 9 Aug 2019 19:43:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99FD8214C6 for ; Fri, 9 Aug 2019 19:43:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726157AbfHITn3 (ORCPT ); Fri, 9 Aug 2019 15:43:29 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:37036 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725927AbfHITn3 (ORCPT ); Fri, 9 Aug 2019 15:43:29 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id B6E96142CA79C; Fri, 9 Aug 2019 12:43:28 -0700 (PDT) Date: Fri, 09 Aug 2019 12:43:27 -0700 (PDT) Message-Id: <20190809.124327.1282600811774499704.davem@davemloft.net> To: Jose.Abreu@synopsys.com Cc: netdev@vger.kernel.org, Joao.Pinto@synopsys.com Subject: Re: [PATCH net-next 01/12] net: stmmac: Get correct timestamp values from XGMAC From: David Miller In-Reply-To: <7acdee903b01dd5462f687c31163628cefa0e372.1565375521.git.joabreu@synopsys.com> References: <7acdee903b01dd5462f687c31163628cefa0e372.1565375521.git.joabreu@synopsys.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Fri, 09 Aug 2019 12:43:29 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Jose Abreu Date: Fri, 9 Aug 2019 20:36:09 +0200 > + void __iomem *ioaddr = hw->pcsr; > + int count = 0; > + u32 value; > + > + do { > + if (readl_poll_timeout_atomic(ioaddr + XGMAC_TIMESTAMP_STATUS, > + value, value & XGMAC_TXTSC, > + 100, 10000)) > + break; > + > + *ts = readl(ioaddr + XGMAC_TXTIMESTAMP_NSEC) & XGMAC_TXTSSTSLO; > + *ts += readl(ioaddr + XGMAC_TXTIMESTAMP_SEC) * 1000000000ULL; > + } while (count++); > + > + if (count) > + return 0; > + return -EBUSY; This is a very strange construct, the loop never executes more than once. Simplified it is essentially: if (readl_poll_timeout_atomic(ioaddr + XGMAC_TIMESTAMP_STATUS, value, value & XGMAC_TXTSC, 100, 10000)) return -EBUSY; *ts = readl(ioaddr + XGMAC_TXTIMESTAMP_NSEC) & XGMAC_TXTSSTSLO; *ts += readl(ioaddr + XGMAC_TXTIMESTAMP_SEC) * 1000000000ULL; return 0; Don't make the code more complicated than it needs to be, there is no reason to use a loop here. And using a loop makes it look like the loop is the polling/timeout construct, when it isn't, because readl_poll_timeout_atomic() is serving that purpose.