From patchwork Tue Mar 31 17:15:04 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Todd Previte X-Patchwork-Id: 6132891 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 75CD69F2EC for ; Tue, 31 Mar 2015 17:15:33 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AB6382017D for ; Tue, 31 Mar 2015 17:15:32 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id D247C2018E for ; Tue, 31 Mar 2015 17:15:30 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 142F76E74E; Tue, 31 Mar 2015 10:15:30 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mail-pd0-f170.google.com (mail-pd0-f170.google.com [209.85.192.170]) by gabe.freedesktop.org (Postfix) with ESMTP id 609656E746; Tue, 31 Mar 2015 10:15:25 -0700 (PDT) Received: by pdmh5 with SMTP id h5so14484918pdm.3; Tue, 31 Mar 2015 10:15:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=dO7uzPm8W54VuNzKfbgCBZcO+85QOr6F6m4VcOuR3jo=; b=yOv33PdaKTIvvoKyGms+z/zbXSLH747w02AKXHfnb7FTHFlewhgYnCR/CG7DgKn7+K bnyAIK5g8xuGzvO9cud4z2Yz/Hm8la0yt2o0IVdSIYO/IwBgJPRCyoWRK9EdTX8fuDWF 53G8bmvCkmGvophjGeyVi8/ePD/Seay51152hlWg8hns3VHCZsXQpT+e+Wv0pgZZ769B AEg/y+EqybR39icSq3VBPa/dZt1egsT5ApPDW82o1tvMQ1A+B8x1LHbm6LFwm0unKIFs os0KR3yPrzcsXblPY2NVL6DTr58Ctk+7BMnp7M4/6g5VLe3Fh3EgweP1XBTGC9YeBe+4 8q9Q== X-Received: by 10.68.132.233 with SMTP id ox9mr69255261pbb.83.1427822125155; Tue, 31 Mar 2015 10:15:25 -0700 (PDT) Received: from localhost.localdomain (ip70-162-72-208.ph.ph.cox.net. [70.162.72.208]) by mx.google.com with ESMTPSA id ae7sm13897438pac.19.2015.03.31.10.15.24 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 31 Mar 2015 10:15:24 -0700 (PDT) From: Todd Previte To: intel-gfx@lists.freedesktop.org Date: Tue, 31 Mar 2015 10:15:04 -0700 Message-Id: <1427822106-29617-8-git-send-email-tprevite@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1427822106-29617-1-git-send-email-tprevite@gmail.com> References: <1427822106-29617-1-git-send-email-tprevite@gmail.com> Cc: dri-devel@lists.freedesktop.org Subject: [Intel-gfx] [PATCH 7/9] drm/i915: Fix for DP CTS test 4.2.2.5 - I2C DEFER handling 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-Spam-Status: No, score=-4.1 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, T_DKIM_INVALID, T_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 For test 4.2.2.5 to pass per the Link CTS Core 1.2 rev1.1 spec, the source device must attempt at least 7 times to read the EDID when it receives an I2C defer. The normal DRM code makes only 7 retries, regardless of whether or not the response is a native defer or an I2C defer. Test 4.2.2.5 fails since there are native defers interspersed with the I2C defers which results in less than 7 EDID read attempts. The solution is to decrement the retry counter when an I2C DEFER is returned such that another read attempt will be made. This situation should normally only occur in compliance testing, however, as a worse case real-world scenario, it would result in 13 attempts ( 6 native defers, 7 I2C defers) for a single transaction to complete. The net result is a slightly slower response to an EDID read that shouldn't significantly impact overall performance. Signed-off-by: Todd Previte Cc: dri-devel@lists.freedesktop.org --- drivers/gpu/drm/drm_dp_helper.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 79968e3..0539758 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -469,6 +469,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) case DP_AUX_I2C_REPLY_DEFER: DRM_DEBUG_KMS("I2C defer\n"); aux->i2c_defer_count++; + /* DP Compliance Test 4.2.2.5 Requirement: + * Must have at least 7 retries for I2C defers on the + * transaction to pass this test + */ + retry--; usleep_range(400, 500); continue;