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=-8.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT 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 3F77DC48BD5 for ; Tue, 25 Jun 2019 18:03:27 +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 199CE20883 for ; Tue, 25 Jun 2019 18:03:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="bmBVCibc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 199CE20883 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.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-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=GEB9tWEzctVzm/kyf6xYAkWqxLwWPV6MFD+PrqP9AQ8=; b=bmBVCibcFTnr0Lus2emEaCFLsq bynRHmiSXkaEcam6eQiJqhB1TwyTz4F2Z6iyleIPCom/8mbELJ8l/OYFeM5cuQSJsztWDe93bvDF/ VY2ecJKA+s7yshvARHlYwo1uZoNkHOH0qrNjcN8SD/BQyqiftk9nECUh6XOsfejV1be6ozTc8T5nY w9fxoe93xRGyXZLwhA3LJeVvOUcAURjYXooduBOcDFY+8C2SzGdsxQLSdDuPeejrg5FBEIH1e0XkC Ca1Vv1FMvZam7nEXj3SV9e7TMH+kBBCzxdcW8ZukD+VCorFOQrNUrT38ZjyMp37RC9jEPM8M/ZA8x S4lO6s2g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hfpmn-0005tV-7I; Tue, 25 Jun 2019 18:03:18 +0000 Received: from bhuna.collabora.co.uk ([2a00:1098:0:82:1000:25:2eeb:e3e3]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hfpmB-0005Or-Vn for linux-arm-kernel@lists.infradead.org; Tue, 25 Jun 2019 18:02:42 +0000 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: bbeckett) with ESMTPSA id CE79E28A3F3 From: Robert Beckett To: dri-devel@lists.freedesktop.org Subject: [PATCH v3 1/4] drm/vblank: warn on sending stale event Date: Tue, 25 Jun 2019 18:59:12 +0100 Message-Id: X-Mailer: git-send-email 2.18.0 In-Reply-To: References: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190625_110240_161289_800358E8 X-CRM114-Status: GOOD ( 10.85 ) 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: Robert Beckett , Fabio Estevam , Daniel Vetter , Maxime Ripard , Shawn Guo , Sascha Hauer , Maarten Lankhorst , linux-kernel@vger.kernel.org, David Airlie , NXP Linux Team , Philipp Zabel , Sean Paul , Pengutronix Kernel Team , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Warn when about to send stale vblank info and add advice to documentation on how to avoid. Signed-off-by: Robert Beckett --- drivers/gpu/drm/drm_vblank.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 603ab105125d..7dabb2bdb733 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -918,6 +918,19 @@ EXPORT_SYMBOL(drm_crtc_arm_vblank_event); * * See drm_crtc_arm_vblank_event() for a helper which can be used in certain * situation, especially to send out events for atomic commit operations. + * + * Care should be taken to avoid stale timestamps. If: + * - your driver has vblank support (i.e. dev->num_crtcs > 0) + * - the vblank irq is off (i.e. no one called drm_crtc_vblank_get) + * - from the vblank code's pov the pipe is still running (i.e. not + * in-between a drm_crtc_vblank_off()/on() pair) + * If all of these conditions hold then drm_crtc_send_vblank_event is + * going to give you a garbage timestamp and and sequence number (the last + * recorded before the irq was disabled). If you call drm_crtc_vblank_get/put + * around it, or after vblank_off, then either of those will have rolled things + * forward for you. + * So, drivers should call drm_crtc_vblank_off() before this function in their + * crtc atomic_disable handlers. */ void drm_crtc_send_vblank_event(struct drm_crtc *crtc, struct drm_pending_vblank_event *e) @@ -925,8 +938,12 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc, struct drm_device *dev = crtc->dev; u64 seq; unsigned int pipe = drm_crtc_index(crtc); + struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; ktime_t now; + WARN_ONCE(dev->num_crtcs > 0 && !vblank->enabled && !vblank->inmodeset, + "sending stale vblank info\n"); + if (dev->num_crtcs > 0) { seq = drm_vblank_count_and_time(dev, pipe, &now); } else { -- 2.18.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel