From patchwork Fri Oct 21 15:55:45 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Zanoni, Paulo R" X-Patchwork-Id: 9389561 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7BB03607D0 for ; Fri, 21 Oct 2016 15:55:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6E3282A076 for ; Fri, 21 Oct 2016 15:55:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 62ACD2A08C; Fri, 21 Oct 2016 15:55:57 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E39952A076 for ; Fri, 21 Oct 2016 15:55:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 32CC76ED67; Fri, 21 Oct 2016 15:55:56 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1E54C6ED60 for ; Fri, 21 Oct 2016 15:55:54 +0000 (UTC) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga103.jf.intel.com with ESMTP; 21 Oct 2016 08:55:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,377,1473145200"; d="scan'208";a="182354281" Received: from przanoni-mobl.amr.corp.intel.com ([10.254.184.124]) by fmsmga004.fm.intel.com with ESMTP; 21 Oct 2016 08:55:52 -0700 From: Paulo Zanoni To: intel-gfx@lists.freedesktop.org Date: Fri, 21 Oct 2016 13:55:45 -0200 Message-Id: <1477065346-13736-1-git-send-email-paulo.r.zanoni@intel.com> X-Mailer: git-send-email 2.7.4 Cc: stable@vger.kernel.org#v4.6+, Paulo Zanoni Subject: [Intel-gfx] [PATCH 1/2] drm/i915/fbc: fix CFB size calculation for gen8+ X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Broadwell and newer actually compress up to 2560 lines instead of 2048 (as documented in the FBC_CTL page). If we don't take this into consideration we end up reserving too little stolen memory for the CFB, so we may allocate something else (such as a ring) right after what we reserved, and the hardware will overwrite it with the contents of the CFB when FBC is active, causing GPU hangs. Another possibility is that the CFB may be allocated at the very end of the available space, so the CFB will overlap the reserved stolen area, leading to FIFO underruns. This bug has always been a problem on BDW (the only affected platform where FBC is enabled by default), but it's much easier to reproduce since the following commit: commit c58b735fc762e891481e92af7124b85cb0a51fce Author: Chris Wilson Date: Thu Aug 18 17:16:57 2016 +0100 drm/i915: Allocate rings from stolen Of course, you can only reproduce the bug if your screen is taller than 2048 lines. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98213 Fixes: a98ee79317b4 ("drm/i915/fbc: enable FBC by default on HSW and BDW") Cc: # v4.6+ Signed-off-by: Paulo Zanoni Reviewed-by: Ville Syrjälä --- drivers/gpu/drm/i915/intel_fbc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c index 617189a..6345cb8 100644 --- a/drivers/gpu/drm/i915/intel_fbc.c +++ b/drivers/gpu/drm/i915/intel_fbc.c @@ -104,8 +104,10 @@ static int intel_fbc_calculate_cfb_size(struct drm_i915_private *dev_priv, int lines; intel_fbc_get_plane_source_size(cache, NULL, &lines); - if (INTEL_INFO(dev_priv)->gen >= 7) + if (INTEL_GEN(dev_priv) == 7) lines = min(lines, 2048); + else if (INTEL_GEN(dev_priv) >= 8) + lines = min(lines, 2560); /* Hardware needs the full buffer stride, not just the active area. */ return lines * cache->fb.stride;