From patchwork Mon Sep 15 18:52:17 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Drake X-Patchwork-Id: 4907391 Return-Path: X-Original-To: patchwork-linux-samsung-soc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E0DB99F32F for ; Mon, 15 Sep 2014 18:49:52 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4556A201CE for ; Mon, 15 Sep 2014 18:52:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DEE6B201B4 for ; Mon, 15 Sep 2014 18:52:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185AbaIOSw3 (ORCPT ); Mon, 15 Sep 2014 14:52:29 -0400 Received: from mail-yk0-f177.google.com ([209.85.160.177]:34046 "EHLO mail-yk0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753571AbaIOSw2 (ORCPT ); Mon, 15 Sep 2014 14:52:28 -0400 Received: by mail-yk0-f177.google.com with SMTP id 79so2327442ykr.36 for ; Mon, 15 Sep 2014 11:52:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=YgjNwaED0Hem0KYuaCM5B+yHAISowRSgzfVtmDXJf3Y=; b=KHHJKcYzmNbK6yOcJLu6UF3CQEGnA7eIcL4rFtTImsof4Z4Iqg+ogwzUQvMtDR1aTP Y+EOO646VIqgzrTmLZ1h/J2fVK2NG7MM52HB4W2a+GkhKHs+4xOEQx3wgka8pXfTnU1f /8GT+aICL5Iuo3DKXTqJU+L3G5yMFf9d70S/mJq31fcgkUqLOwANW6V8+E9B+UnA1cEu QxqeTv6/yAPIc3X8aRo4DCI8ZrXdDpWWm3o61BR4GBwyL6qMtzVjz+Isu8svTRCuqkda hzJAfXtxbtXGm3bDRaVAEn9S3slkDfAuwwIfJFPWZyAAkMPnxkLgZD7kzA1JmtX30wfh xReQ== X-Gm-Message-State: ALoCoQkSO64Le2dk5b82YE9Z6Fwf1gfLF408ypVoqPvU0JSBamO1UWa4R3CO/s5ZIVs1+lXbxrRq X-Received: by 10.236.190.133 with SMTP id e5mr36369007yhn.13.1410807147625; Mon, 15 Sep 2014 11:52:27 -0700 (PDT) Received: from dsd-ubuntu.gallo.pinto ([190.181.183.137]) by mx.google.com with ESMTPSA id g22sm5555558yhb.18.2014.09.15.11.52.24 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 15 Sep 2014 11:52:26 -0700 (PDT) From: Daniel Drake To: inki.dae@samsung.com, jy0922.shim@samsung.com, sw0312.kim@samsung.com, kyungmin.park@samsung.com Cc: dri-devel@lists.freedesktop.org, a.hajda@samsung.com, linux-samsung-soc@vger.kernel.org Subject: [PATCH] drm/exynos: fix plane-framebuffer linkage Date: Mon, 15 Sep 2014 12:52:17 -0600 Message-Id: <1410807137-8323-1-git-send-email-drake@endlessm.com> X-Mailer: git-send-email 1.9.1 Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Pageflipping currently causes some inconsistencies that lead to crashes. Just run an app that causes a CRTC pageflip in a raw X session and check that it exits cleanly and can be restarted - you'll see crashes like: Unable to handle kernel NULL pointer dereference at virtual address 00000334 PC is at exynos_drm_crtc_plane_commit+0x20/0x40 LR is at exynos_drm_crtc_plane_commit+0x20/0x40 [] (exynos_drm_crtc_plane_commit) from [] (exynos_drm_crtc_commit+0x44/0x70) [] (exynos_drm_crtc_commit) from [] (exynos_drm_crtc_mode_set_commit.isra.2+0xb4/0xc4) [] (exynos_drm_crtc_mode_set_commit.isra.2) from [] (exynos_drm_crtc_page_flip+0x140/0x1a8) [] (exynos_drm_crtc_page_flip) from [] (drm_mode_page_flip_ioctl+0x224/0x2dc) [] (drm_mode_page_flip_ioctl) from [] (drm_ioctl+0x338/0x4fc) These crashes happen because drm_plane_force_disable has previously set plane->crtc to NULL. When drm_mode_page_flip_ioctl() is used to flip another framebuffer onto the primary plane, crtc->primary->fb is correctly updated (this is a virtual plane created by plane_helper), but plane->fb is not (this plane is the real one, created by exynos_drm_crtc_create). We then come to handle rmfb of the backbuffer, which the "real" primary plane is incorrectly pointing at. So drm_framebuffer_remove() decides that the buffer is actually active on a plane and force-disables the plane. Ensuring that plane->fb is kept up-to-date solves that issue, but exposes a reference counting problem. Now we see crashes when rmfb is called on the front-buffer, because the rmfb code expects to drop 3 references here, and there are only 2. That can be fixed by adopting the reference management found in omapdrm: Framebuffer references are not taken directly in crtc mode_set context, but rather in the context of updating the plane, which also covers flips. Like omapdrm we also unreference the old framebuffer here. Signed-off-by: Daniel Drake --- drivers/gpu/drm/exynos/exynos_drm_crtc.c | 12 ++---------- drivers/gpu/drm/exynos/exynos_drm_plane.c | 8 ++++++++ 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c index b68e58f..7aa9dee 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c @@ -140,16 +140,8 @@ exynos_drm_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode, if (manager->ops->mode_set) manager->ops->mode_set(manager, &crtc->mode); - ret = exynos_plane_mode_set(plane, crtc, crtc->primary->fb, 0, 0, crtc_w, crtc_h, - x, y, crtc_w, crtc_h); - if (ret) - return ret; - - plane->crtc = crtc; - plane->fb = crtc->primary->fb; - drm_framebuffer_reference(plane->fb); - - return 0; + return exynos_plane_mode_set(plane, crtc, crtc->primary->fb, 0, 0, + crtc_w, crtc_h, x, y, crtc_w, crtc_h); } static int exynos_drm_crtc_mode_set_commit(struct drm_crtc *crtc, int x, int y, diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c index 8371cbd..df27e35 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_plane.c +++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c @@ -139,6 +139,14 @@ int exynos_plane_mode_set(struct drm_plane *plane, struct drm_crtc *crtc, overlay->crtc_x, overlay->crtc_y, overlay->crtc_width, overlay->crtc_height); + if (plane->fb) + drm_framebuffer_unreference(plane->fb); + + drm_framebuffer_reference(fb); + + plane->fb = fb; + plane->crtc = crtc; + exynos_drm_crtc_plane_mode_set(crtc, overlay); return 0;