From patchwork Thu Apr 21 21:18:19 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 725841 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p3LLMX5i009505 for ; Thu, 21 Apr 2011 21:22:53 GMT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 34A9E9F0E2 for ; Thu, 21 Apr 2011 14:22:33 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (server109-228-6-236.live-servers.net [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id 2946F9E861 for ; Thu, 21 Apr 2011 14:18:52 -0700 (PDT) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.66.37; Received: from arrandale.alporthouse.com (unverified [78.156.66.37]) by fireflyinternet.com (Firefly Internet SMTP) with ESMTP id 32744341-1500050 for multiple; Thu, 21 Apr 2011 22:18:38 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Thu, 21 Apr 2011 22:18:19 +0100 Message-Id: <1303420712-6369-5-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1303420712-6369-1-git-send-email-chris@chris-wilson.co.uk> References: <1303420712-6369-1-git-send-email-chris@chris-wilson.co.uk> X-Originating-IP: 78.156.66.37 Cc: stable@kernel.org Subject: [Intel-gfx] [PATCH 04/17] drm/i915/dp: Be paranoid in case we disable a DP before it is attached X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Thu, 21 Apr 2011 21:22:53 +0000 (UTC) Given that the hardware may be left in a random condition by the BIOS, it is conceivable that we then attempt to clear the DP_PIPEB_SELECT bit without us ever enabling/attaching the DP encoder to a pipe. Thus causing a NULL deference when we attempt to wait for a vblank on that crtc. Reported-and-tested-by: Bryan Christ Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36314 Signed-off-by: Chris Wilson Cc: stable@kernel.org --- drivers/gpu/drm/i915/intel_dp.c | 17 +++++++++++++++-- 1 files changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index cb8578b..a4d8031 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1470,7 +1470,8 @@ intel_dp_link_down(struct intel_dp *intel_dp) if (!HAS_PCH_CPT(dev) && I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) { - struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.base.crtc); + struct drm_crtc *crtc = intel_dp->base.base.crtc; + /* Hardware workaround: leaving our transcoder select * set to transcoder B while it's off will prevent the * corresponding HDMI output on transcoder A. @@ -1485,7 +1486,19 @@ intel_dp_link_down(struct intel_dp *intel_dp) /* Changes to enable or select take place the vblank * after being written. */ - intel_wait_for_vblank(dev, intel_crtc->pipe); + if (crtc == NULL) { + /* We can arrive here never having been attached + * to a CRTC, for instance, due to inheriting + * random state from the BIOS. + * + * If the pipe is not running, play safe and + * wait for the clocks to stabilise before + * continuing. + */ + POSTING_READ(intel_dp->output_reg); + msleep(50); + } else + intel_wait_for_vblank(dev, to_intel_crtc(crtc)->pipe); } I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);