From patchwork Tue Apr 5 09:24:16 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 686371 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 p359QSqm014559 for ; Tue, 5 Apr 2011 09:26:48 GMT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A02BB9ECE3 for ; Tue, 5 Apr 2011 02:26:28 -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 7739F9EB76 for ; Tue, 5 Apr 2011 02:24:29 -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 31147418-1500050 for multiple; Tue, 05 Apr 2011 10:24:21 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 5 Apr 2011 10:24:16 +0100 Message-Id: <1301995458-2699-4-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1301995458-2699-1-git-send-email-chris@chris-wilson.co.uk> References: <1301995458-2699-1-git-send-email-chris@chris-wilson.co.uk> X-Originating-IP: 78.156.66.37 Subject: [Intel-gfx] [PATCH 3/5] drm/i915/crt: Remove 0xa0 probe for VGA 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]); Tue, 05 Apr 2011 09:26:48 +0000 (UTC) This is a moral revert of 6ec3d0c0e9c0c605696e91048eebaca7b0c36695. Following the fix to reset the GMBUS controller after a NAK, we finally utilize the 0xa0 probe for a CRT connection. And discover that it the code is broken. Shock. There are a number of issues, but following a key insight from Dave Airlie, that 0xA0 is an invalid address on a 7-bit bus (though not if we were to enable 10-bit addressing), and would look like the EDID port 0x50, it is possible to see where the confusion starts. In short, a write to 0xA0 is accepted by the GMBUS controller which we interpreted as meaning the existence of a connection (a slave on the other end of the wire ACKing the write). That was false. During testing with a broken GMBUS implementation, which never reset an earlier NAK, this test always reported a NAK and so we proceeded on to the next test. Reported-and-tested-by: Sitsofe Wheeler Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35904 Reported-and-tested-by: Riccardo Magliocchetti Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=32612 Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/intel_crt.c | 20 -------------------- 1 files changed, 0 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c index 49ce713..e17bc6b 100644 --- a/drivers/gpu/drm/i915/intel_crt.c +++ b/drivers/gpu/drm/i915/intel_crt.c @@ -269,21 +269,6 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector) return ret; } -static bool intel_crt_ddc_probe(struct drm_i915_private *dev_priv, int ddc_bus) -{ - u8 buf; - struct i2c_msg msgs[] = { - { - .addr = 0xA0, - .flags = 0, - .len = 1, - .buf = &buf, - }, - }; - /* DDC monitor detect: Does it ACK a write to 0xA0? */ - return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 1) == 1; -} - static bool intel_crt_detect_ddc(struct drm_connector *connector) { struct intel_crt *crt = intel_attached_crt(connector); @@ -293,11 +278,6 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector) if (crt->base.type != INTEL_OUTPUT_ANALOG) return false; - if (intel_crt_ddc_probe(dev_priv, dev_priv->crt_ddc_pin)) { - DRM_DEBUG_KMS("CRT detected via DDC:0xa0\n"); - return true; - } - if (intel_ddc_probe(&crt->base, dev_priv->crt_ddc_pin)) { struct edid *edid; bool is_digital = false;