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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 48335C43603 for ; Thu, 12 Dec 2019 00:50:09 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 166A6208C3 for ; Thu, 12 Dec 2019 00:50:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DSzMNMgy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 166A6208C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=O0t6/bJjSaQuliaCWVxqFY1No6pkw+CmcbC1bqoQ2Vc=; b=DSzMNMgyMfDCwcyq17VPiP2Wo PHsruHGNV/rosdEwC4VR73g6zIJmolWdbNag6vP/gDGWAndup6ZH0JxlzNwNkj6w0T+clDP5AmIOU MEfy2F5Cpng0VXKBSeS/k5FtJQyv83IMOQW6tX7bKxmMAtE7OMAXEUk3nHg9Q8XZ0IenVkL0lDvmc JsEiASX3xkb71BBO9/iNcX00YhD8VDZGgCdvfBpeTsbJYOxAq4lkKwb72UaAGAMdzLd0ZHDLx3+jM YgfXPz0X6W8h4CIMwFw0MYf/aCIDvjQQPjwlM63W2n59Mk2GIWmCJAs0X8pHOfJNtoItRfwO3NsaU VfvHVlp3w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ifCgC-0006tr-AC; Thu, 12 Dec 2019 00:50:08 +0000 Received: from mga03.intel.com ([134.134.136.65]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ifCg9-0006NZ-3L for linux-arm-kernel@lists.infradead.org; Thu, 12 Dec 2019 00:50:06 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Dec 2019 16:50:04 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,303,1571727600"; d="scan'208";a="388124032" Received: from yoojae-mobl1.amr.corp.intel.com (HELO [10.7.153.143]) ([10.7.153.143]) by orsmga005.jf.intel.com with ESMTP; 11 Dec 2019 16:50:04 -0800 Subject: Re: [PATCH v11 06/14] peci: Add Aspeed PECI adapter driver To: Andy Shevchenko References: <20191211194624.2872-1-jae.hyun.yoo@linux.intel.com> <20191211194624.2872-7-jae.hyun.yoo@linux.intel.com> <20191211202818.GD32742@smile.fi.intel.com> From: Jae Hyun Yoo Message-ID: Date: Wed, 11 Dec 2019 16:50:04 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191211202818.GD32742@smile.fi.intel.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191211_165005_192106_8EC05966 X-CRM114-Status: GOOD ( 23.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Randy Dunlap , Tomer Maimon , devicetree@vger.kernel.org, Frederic Barrat , Mauro Carvalho Chehab , Lee Jones , Eric Sandeen , Lorenzo Pieralisi , Jonathan Corbet , openbmc@lists.ozlabs.org, linux-doc@vger.kernel.org, Kishon Vijay Abraham I , Joel Stanley , "Bryant G . Ly" , Uwe Kleine-Konig , David Kershner , Guenter Roeck , Wu Hao , linux-hwmon@vger.kernel.org, Jean Delvare , Arnd Bergmann , Philippe Ombredanne , Johan Hovold , Tomohiro Kusumi , Rob Herring , Thomas Gleixner , Sagar Dharia , linux-arm-kernel@lists.infradead.org, Juergen Gross , Cyrille Pitchen , Ryan Chen , Andrew Jeffery , Greg Kroah-Hartman , "Darrick J . Wong" , Stephen Boyd , Vinod Koul , Gustavo Pimentel , Andrew Morton , Robin Murphy , "David S . Miller" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Andy, On 12/11/2019 12:28 PM, Andy Shevchenko wrote: > On Wed, Dec 11, 2019 at 11:46:16AM -0800, Jae Hyun Yoo wrote: >> This commit adds Aspeed PECI adapter driver for Aspeed >> AST24xx/25xx/26xx SoCs. > > ... > >> +#define ASPEED_PECI_CMD_IDLE_MASK (ASPEED_PECI_CMD_STS_MASK | \ >> + ASPEED_PECI_CMD_PIN_MON) > > Better looking when the value completely occupies second line without touching > the first. Yes. Will change it. > ... > >> +static int aspeed_peci_check_idle(struct aspeed_peci *priv) >> +{ >> + ulong timeout = jiffies + usecs_to_jiffies(ASPEED_PECI_IDLE_CHECK_TIMEOUT_USEC); >> + u32 cmd_sts; > > Like in the previous patch this one has hard to read timeout loops with inefficient code. > >> + for (;;) { >> + cmd_sts = readl(priv->base + ASPEED_PECI_CMD); >> + if (!(cmd_sts & ASPEED_PECI_CMD_IDLE_MASK)) >> + break; > >> + if (time_after(jiffies, timeout)) { > > This is actually main exit condition (vs. infinite loop). > >> + cmd_sts = readl(priv->base + ASPEED_PECI_CMD); > > This make no sense. If you would like to have one more iteration, just spell it > explicitly. > >> + break; >> + } > >> + usleep_range((ASPEED_PECI_IDLE_CHECK_INTERVAL_USEC >> 2) + 1, >> + ASPEED_PECI_IDLE_CHECK_INTERVAL_USEC); >> + } >> + > >> + return !(cmd_sts & ASPEED_PECI_CMD_IDLE_MASK) ? 0 : -ETIMEDOUT; > > Ditto. > >> +} > > Now look at the other variant: > > do { > ...do something... > if (success) > return 0; > usleep(...); > } while (time_before(...)); > > return -ETIMEDOUT; > > * Easy > * less LOCs > * guaranteed always to be at least one iteration > * has explicitly spelled exit condition > > BUT! > > In this very case you may do even better if you read iopoll.h, i.e > readl_poll_timeout() has this functionality embedded in the macro. > I see. I'll simplify this function like below: #include static inline int aspeed_peci_check_idle(struct aspeed_peci *priv) { u32 cmd_sts; return readl_poll_timeout(priv->base + ASPEED_PECI_CMD, cmd_sts, !(cmd_sts & ASPEED_PECI_CMD_IDLE_MASK), ASPEED_PECI_IDLE_CHECK_INTERVAL_USEC, ASPEED_PECI_IDLE_CHECK_TIMEOUT_USEC); } Thanks a lot for your review! -Jae _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel