From patchwork Mon Mar 29 13:38:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikko Perttunen X-Patchwork-Id: 12170133 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 0EA7AC433E0 for ; Mon, 29 Mar 2021 13:39:19 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 A702B60C3D for ; Mon, 29 Mar 2021 13:39:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A702B60C3D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 659506E43A; Mon, 29 Mar 2021 13:39:13 +0000 (UTC) Received: from mail.kapsi.fi (mail.kapsi.fi [IPv6:2001:67c:1be8::25]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9654C6E43B for ; Mon, 29 Mar 2021 13:39:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=kapsi.fi; s=20161220; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=oUjncLS3gCDXw94Lt9M8obnU5O3nF6FFg8UrSvy5aXQ=; b=LLmlqY86bAg2E4m26vBnTc2Xu7 8ZGSuQWmUJZb+Y3WWZ5TvKk7OSznG1o4uLe4wtFuCfozO1puu6GRxqrzEBfYolvxRLVvriB8RMMV1 FtYce984kN0eO81+9pCz1g7Q9GZmZko/wYq+ec3rT3U93xCb6qdN+TCPKMCXqSH0fWIko34kZMr7q ZcC/42t+XUQCnC2kfnP7z+dfsuH+UEOozytq8ZZINROuiE0sHTpIXyDSg+cnEaPdzgvCLs7tAQa7v GjZVl6CeL3Yc631ezY/LYI1pm3Jl2JGTXzlvkIyfRox6gcCZJbp+smrgvOTg1zyl1tdOaXz872lqQ H6kJe34Q==; Received: from dsl-hkibng22-54f986-236.dhcp.inet.fi ([84.249.134.236] helo=toshino.localdomain) by mail.kapsi.fi with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1lQs6n-0000Yj-J7; Mon, 29 Mar 2021 16:39:09 +0300 From: Mikko Perttunen To: thierry.reding@gmail.com, jonathanh@nvidia.com Subject: [PATCH v6 05/10] gpu: host1x: Use HW-equivalent syncpoint expiration check Date: Mon, 29 Mar 2021 16:38:31 +0300 Message-Id: <20210329133836.2115236-6-mperttunen@nvidia.com> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210329133836.2115236-1-mperttunen@nvidia.com> References: <20210329133836.2115236-1-mperttunen@nvidia.com> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 84.249.134.236 X-SA-Exim-Mail-From: mperttunen@nvidia.com X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-tegra@vger.kernel.org, dri-devel@lists.freedesktop.org, Mikko Perttunen Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Make syncpoint expiration checks always use the same logic used by the hardware. This ensures that there are no race conditions that could occur because of the hardware triggering a syncpoint interrupt and then the driver disagreeing. One situation where this could occur is if a job incremented a syncpoint too many times -- then the hardware would trigger an interrupt, but the driver would assume that a syncpoint value greater than the syncpoint's max value is in the future, and not clean up the job. Signed-off-by: Mikko Perttunen Tested-by: Dmitry Osipenko --- drivers/gpu/host1x/syncpt.c | 51 ++----------------------------------- 1 file changed, 2 insertions(+), 49 deletions(-) diff --git a/drivers/gpu/host1x/syncpt.c b/drivers/gpu/host1x/syncpt.c index f061dfd5bbc7..8da4bbce8b9d 100644 --- a/drivers/gpu/host1x/syncpt.c +++ b/drivers/gpu/host1x/syncpt.c @@ -321,59 +321,12 @@ EXPORT_SYMBOL(host1x_syncpt_wait); bool host1x_syncpt_is_expired(struct host1x_syncpt *sp, u32 thresh) { u32 current_val; - u32 future_val; smp_rmb(); current_val = (u32)atomic_read(&sp->min_val); - future_val = (u32)atomic_read(&sp->max_val); - - /* Note the use of unsigned arithmetic here (mod 1<<32). - * - * c = current_val = min_val = the current value of the syncpoint. - * t = thresh = the value we are checking - * f = future_val = max_val = the value c will reach when all - * outstanding increments have completed. - * - * Note that c always chases f until it reaches f. - * - * Dtf = (f - t) - * Dtc = (c - t) - * - * Consider all cases: - * - * A) .....c..t..f..... Dtf < Dtc need to wait - * B) .....c.....f..t.. Dtf > Dtc expired - * C) ..t..c.....f..... Dtf > Dtc expired (Dct very large) - * - * Any case where f==c: always expired (for any t). Dtf == Dcf - * Any case where t==c: always expired (for any f). Dtf >= Dtc (because Dtc==0) - * Any case where t==f!=c: always wait. Dtf < Dtc (because Dtf==0, - * Dtc!=0) - * - * Other cases: - * - * A) .....t..f..c..... Dtf < Dtc need to wait - * A) .....f..c..t..... Dtf < Dtc need to wait - * A) .....f..t..c..... Dtf > Dtc expired - * - * So: - * Dtf >= Dtc implies EXPIRED (return true) - * Dtf < Dtc implies WAIT (return false) - * - * Note: If t is expired then we *cannot* wait on it. We would wait - * forever (hang the system). - * - * Note: do NOT get clever and remove the -thresh from both sides. It - * is NOT the same. - * - * If future valueis zero, we have a client managed sync point. In that - * case we do a direct comparison. - */ - if (!host1x_syncpt_client_managed(sp)) - return future_val - thresh >= current_val - thresh; - else - return (s32)(current_val - thresh) >= 0; + + return ((current_val - thresh) & 0x80000000U) == 0U; } int host1x_syncpt_init(struct host1x *host)