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=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 2E8B2C31E4E for ; Fri, 14 Jun 2019 18:17:43 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 10B432177E for ; Fri, 14 Jun 2019 18:17:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10B432177E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id DF044168F; Fri, 14 Jun 2019 18:17:42 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 28B8B143D for ; Fri, 14 Jun 2019 18:17:41 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from Galois.linutronix.de (Galois.linutronix.de [146.0.238.70]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7E7A97C3 for ; Fri, 14 Jun 2019 18:17:40 +0000 (UTC) Received: from p5b06daab.dip0.t-ipconnect.de ([91.6.218.171] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hbqlM-0006Wc-Mn; Fri, 14 Jun 2019 20:17:20 +0200 Date: Fri, 14 Jun 2019 20:17:14 +0200 (CEST) From: Thomas Gleixner To: Ricardo Neri Subject: Re: [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes In-Reply-To: <1558660583-28561-5-git-send-email-ricardo.neri-calderon@linux.intel.com> Message-ID: References: <1558660583-28561-1-git-send-email-ricardo.neri-calderon@linux.intel.com> <1558660583-28561-5-git-send-email-ricardo.neri-calderon@linux.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1, SHORTCIRCUIT=-0.0001 Cc: Kate Stewart , "Ravi V. Shankar" , x86@kernel.org, Ashok Raj , Peter Zijlstra , Philippe Ombredanne , Randy Dunlap , linux-kernel@vger.kernel.org, Stephane Eranian , Ricardo Neri , "Rafael J. Wysocki" , iommu@lists.linux-foundation.org, Tony Luck , "H. Peter Anvin" , Andi Kleen , Borislav Petkov , Ingo Molnar X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Thu, 23 May 2019, Ricardo Neri wrote: > +/** > + * hpet_set_comparator() - Helper function for setting comparator register > + * @num: The timer ID > + * @cmp: The value to be written to the comparator/accumulator > + * @period: The value to be written to the period (0 = oneshot mode) > + * > + * Helper function for updating comparator, accumulator and period values. > + * > + * In periodic mode, HPET needs HPET_TN_SETVAL to be set before writing > + * to the Tn_CMP to update the accumulator. Then, HPET needs a second > + * write (with HPET_TN_SETVAL cleared) to Tn_CMP to set the period. > + * The HPET_TN_SETVAL bit is automatically cleared after the first write. > + * > + * For one-shot mode, HPET_TN_SETVAL does not need to be set. > + * > + * See the following documents: > + * - Intel IA-PC HPET (High Precision Event Timers) Specification > + * - AMD-8111 HyperTransport I/O Hub Data Sheet, Publication # 24674 > + */ > +void hpet_set_comparator(int num, unsigned int cmp, unsigned int period) > +{ > + if (period) { > + unsigned int v = hpet_readl(HPET_Tn_CFG(num)); > + > + hpet_writel(v | HPET_TN_SETVAL, HPET_Tn_CFG(num)); > + } > + > + hpet_writel(cmp, HPET_Tn_CMP(num)); > + > + if (!period) > + return; TBH, I hate this conditional handling. What's wrong with two functions? > + > + /* > + * This delay is seldom used: never in one-shot mode and in periodic > + * only when reprogramming the timer. > + */ > + udelay(1); > + hpet_writel(period, HPET_Tn_CMP(num)); > +} > +EXPORT_SYMBOL_GPL(hpet_set_comparator); Why is this exported? Which module user needs this? Thanks, tglx _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu