From patchwork Mon Nov 12 18:20:41 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Hunter, Jon" X-Patchwork-Id: 1729821 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id 90CFEDFE80 for ; Mon, 12 Nov 2012 18:27:09 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TXygq-0001ol-3f; Mon, 12 Nov 2012 18:24:56 +0000 Received: from arroyo.ext.ti.com ([192.94.94.40]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TXyd0-0007wx-2x for linux-arm-kernel@lists.infradead.org; Mon, 12 Nov 2012 18:21:06 +0000 Received: from dlelxv30.itg.ti.com ([172.17.2.17]) by arroyo.ext.ti.com (8.13.7/8.13.7) with ESMTP id qACIKvHP004611; Mon, 12 Nov 2012 12:20:57 -0600 Received: from DLEE74.ent.ti.com (dlee74.ent.ti.com [157.170.170.8]) by dlelxv30.itg.ti.com (8.13.8/8.13.8) with ESMTP id qACIKvQP016533; Mon, 12 Nov 2012 12:20:57 -0600 Received: from dlelxv23.itg.ti.com (172.17.1.198) by DLEE74.ent.ti.com (157.170.170.8) with Microsoft SMTP Server id 14.1.323.3; Mon, 12 Nov 2012 12:20:56 -0600 Received: from legion.dal.design.ti.com (legion.dal.design.ti.com [128.247.22.53]) by dlelxv23.itg.ti.com (8.13.8/8.13.8) with ESMTP id qACIKuk3011566; Mon, 12 Nov 2012 12:20:56 -0600 Received: from localhost (ula0741266.am.dhcp.ti.com [192.157.144.139]) by legion.dal.design.ti.com (8.11.7p1+Sun/8.11.7) with ESMTP id qACIKuw07443; Mon, 12 Nov 2012 12:20:56 -0600 (CST) From: Jon Hunter To: Tony Lindgren Subject: [PATCH V3 10/13] ARM: OMAP: Fix spurious interrupts when using timer match feature Date: Mon, 12 Nov 2012 12:20:41 -0600 Message-ID: <1352744444-2633-11-git-send-email-jon-hunter@ti.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1352744444-2633-1-git-send-email-jon-hunter@ti.com> References: <1352744444-2633-1-git-send-email-jon-hunter@ti.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20121112_132058_383763_A7E324DD X-CRM114-Status: GOOD ( 12.36 ) X-Spam-Score: -7.6 (-------) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-7.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [192.94.94.40 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Kevin Hilman , Paul Walmsley , linux-omap , Jon Hunter , linux-arm X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The OMAP DMTIMERs can generate an interrupt when the timer counter value matches the value stored in the timer's match register. When using this feature spurious interrupts were seen, because the compare logic is being enabled before the match value is loaded and according to the documentation the match value must be loaded before the compare logic is enable. The reset value for the timer counter and match registers is 0 and hence, by enabling the compare logic before the actual match value is loaded a spurious interrupt can be generated as the reset values match. Signed-off-by: Jon Hunter Acked-by: Santosh Shilimkar --- arch/arm/plat-omap/dmtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c index f0a3c4c..a38e896 100644 --- a/arch/arm/plat-omap/dmtimer.c +++ b/arch/arm/plat-omap/dmtimer.c @@ -584,8 +584,8 @@ int omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable, l |= OMAP_TIMER_CTRL_CE; else l &= ~OMAP_TIMER_CTRL_CE; - omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l); omap_dm_timer_write_reg(timer, OMAP_TIMER_MATCH_REG, match); + omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l); /* Save the context */ timer->context.tclr = l;