From patchwork Sat Sep 5 10:34:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikko Perttunen X-Patchwork-Id: 11758989 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 267B5746 for ; Sat, 5 Sep 2020 10:36:18 +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 EDAD2214D8 for ; Sat, 5 Sep 2020 10:36:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=kapsi.fi header.i=@kapsi.fi header.b="uuFYb2tk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDAD2214D8 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 4AAAA6ED4A; Sat, 5 Sep 2020 10:35:59 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail.kapsi.fi (mail.kapsi.fi [IPv6:2001:67c:1be8::25]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4ABF46ED4A for ; Sat, 5 Sep 2020 10:35:55 +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=cPEpocOG4OtUGfE2OnMDDDp60EvvppcCACpp5KRBhNs=; b=uuFYb2tkN6gtqp+7YJBu27zqia 1VcmW3cv1wmlRw+d4rbRrlPQKkSO+pNT3OYF6wvfkyxm3XcfZxW/XBZjtAtdRD0nfuVfvCMVweL9X +29h27+xb75WiuV9ooxWl0BanOMpM+fbpnYL14Jrc+i5vWuPdg6zsZ4CJRusa7sq7ngYEUZRkqtkm VA9s96ulI1u1fzPdAuwpDbYdW8Zj57Y2OcGY7RbwuIiLIGhDUi/YtZfWd70EdB4DzXniKfgDkFaPS hvw1kYOZNpuv/G3ejI87NsKbGzZ7EKI4GhbssQo0EMjjSH6byYzw/DsRPN/KTFfxJ8fgl2JiS5inc s/h/Op+g==; Received: from dsl-hkibng22-54faab-65.dhcp.inet.fi ([84.250.171.65] helo=toshino.localdomain) by mail.kapsi.fi with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1kEVXw-0003SS-W2; Sat, 05 Sep 2020 13:35:49 +0300 From: Mikko Perttunen To: thierry.reding@gmail.com, jonathanh@nvidia.com, digetx@gmail.com, airlied@linux.ie, daniel@ffwll.ch Subject: [RFC PATCH v2 05/17] gpu: host1x: Use HW-equivalent syncpoint expiration check Date: Sat, 5 Sep 2020 13:34:08 +0300 Message-Id: <20200905103420.3021852-6-mperttunen@nvidia.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200905103420.3021852-1-mperttunen@nvidia.com> References: <20200905103420.3021852-1-mperttunen@nvidia.com> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 84.250.171.65 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, talho@nvidia.com, bhuntsman@nvidia.com, 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 --- 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 7cb80d4768b1..5329a0886d29 100644 --- a/drivers/gpu/host1x/syncpt.c +++ b/drivers/gpu/host1x/syncpt.c @@ -306,59 +306,12 @@ 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)