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=-2.2 required=3.0 tests=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 D9F4EC2D0C6 for ; Thu, 12 Dec 2019 00:50:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B397B24653 for ; Thu, 12 Dec 2019 00:50:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727360AbfLLAuF (ORCPT ); Wed, 11 Dec 2019 19:50:05 -0500 Received: from mga04.intel.com ([192.55.52.120]:30335 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726673AbfLLAuF (ORCPT ); Wed, 11 Dec 2019 19:50:05 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.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 Cc: Rob Herring , Greg Kroah-Hartman , Lee Jones , Jean Delvare , Guenter Roeck , Mark Rutland , Joel Stanley , Andrew Jeffery , Jonathan Corbet , Gustavo Pimentel , Kishon Vijay Abraham I , Lorenzo Pieralisi , "Darrick J . Wong" , Eric Sandeen , Arnd Bergmann , Wu Hao , Tomohiro Kusumi , "Bryant G . Ly" , Frederic Barrat , "David S . Miller" , Mauro Carvalho Chehab , Andrew Morton , Randy Dunlap , Philippe Ombredanne , Vinod Koul , Stephen Boyd , David Kershner , Uwe Kleine-Konig , Sagar Dharia , Johan Hovold , Thomas Gleixner , Juergen Gross , Cyrille Pitchen , Tomer Maimon , linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, openbmc@lists.ozlabs.org, Robin Murphy , Ryan Chen 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-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.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