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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 4BBB7C43444 for ; Tue, 8 Jan 2019 19:27:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 181DA217D9 for ; Tue, 8 Jan 2019 19:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975645; bh=dLHeRF3DnDi6sYm+vAhqjXeAt1fDLejieIq/2WhlCLE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gtinPeNNR8Jy7MQLrNHAGXjBw2oPCz0Cvr7Cws9srdqGsV2Sv9i7HUFOdILpSPh4d FFkQK/xG3g+JRumuBB8U4LBU7w07Y1XZMe5ggzej82Kq39kbrXJz3CQN6TC2/Avx0r ZOiohXuJrsj1VnH9UITqwMKh03VO8AwXquRvNa1k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729634AbfAHT1Y (ORCPT ); Tue, 8 Jan 2019 14:27:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:33412 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729599AbfAHT1U (ORCPT ); Tue, 8 Jan 2019 14:27:20 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 61B242176F; Tue, 8 Jan 2019 19:27:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975640; bh=dLHeRF3DnDi6sYm+vAhqjXeAt1fDLejieIq/2WhlCLE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gXix5M1X7rWciplcTsqRgU3CWmG8rjjf7/k4EOUfBFBZDg8LgT1NRc1f4tdl+Nr0e yqN4LK5dYwVr5nh8ArOB7t3nNakEgZ2KApihU8WisyZZhU8emU5XLjHziTHPi9SoF0 RsHd/fNGIvRX9yZf692CZzb+vK99hOtXFpr8ahJA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Maarten Lankhorst , Sasha Levin , dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 4.20 026/117] drm/atomic-helper: Complete fake_commit->flip_done potentially earlier Date: Tue, 8 Jan 2019 14:24:54 -0500 Message-Id: <20190108192628.121270-26-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108192628.121270-1-sashal@kernel.org> References: <20190108192628.121270-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ville Syrjälä [ Upstream commit 2de42f79bb21a412f40ade8831eb6fc445cb78a4 ] Consider the following scenario: 1. nonblocking enable crtc 2. wait for the event 3. nonblocking disable crtc On i915 this can lead to a spurious -EBUSY from step 3 on account of non-enabled planes getting the fake_commit in step 1 and we don't complete the fake_commit-> flip_done until drm_atomic_helper_commit_hw_done() which can happen a long time after the flip event was sent out. This will become somewhat easy to hit on SKL+ once we start to add all the planes for the crtc to every modeset commit for the purposes of forcing a watermark register programming [1]. To make the race a little less pronounced let's complete fake_commit->flip_done after drm_atomic_helper_wait_for_flip_done(). For the single crtc case this should make the race quite theoretical, assuming drm_atomic_helper_wait_for_flip_done() actually has to wait for the real commit flip_done. In case the real commit flip_done gets completed singificantly before drm_atomic_helper_wait_for_flip_done(), or we are dealing with multiple crtcs whose vblanks don't line up nicely the race still exists. [1] https://patchwork.freedesktop.org/patch/262670/ Cc: Maarten Lankhorst Fixes: 080de2e5be2d ("drm/atomic: Check for busy planes/connectors before setting the commit") Testcase: igt/kms_cursor_legacy/*nonblocking-modeset-vs-cursor-atomic Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20181122143412.11655-1-ville.syrjala@linux.intel.com Reviewed-by: Maarten Lankhorst Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_atomic_helper.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index d8b526b7932c..b4e292a56046 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1445,6 +1445,9 @@ void drm_atomic_helper_wait_for_flip_done(struct drm_device *dev, DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n", crtc->base.id, crtc->name); } + + if (old_state->fake_commit) + complete_all(&old_state->fake_commit->flip_done); } EXPORT_SYMBOL(drm_atomic_helper_wait_for_flip_done); -- 2.19.1