From patchwork Wed Apr 1 17:52:58 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Todd Previte X-Patchwork-Id: 6141631 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id F3CC1BF4A6 for ; Wed, 1 Apr 2015 17:53:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 289F420361 for ; Wed, 1 Apr 2015 17:53:17 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 3BBEA2035E for ; Wed, 1 Apr 2015 17:53:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 86B516E8D7; Wed, 1 Apr 2015 10:53:14 -0700 (PDT) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail-pa0-f52.google.com (mail-pa0-f52.google.com [209.85.220.52]) by gabe.freedesktop.org (Postfix) with ESMTP id F00F96E8D7 for ; Wed, 1 Apr 2015 10:53:12 -0700 (PDT) Received: by patj18 with SMTP id j18so58745377pat.2 for ; Wed, 01 Apr 2015 10:53:12 -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=ncGNjAmweDGho2iNUV88A2Ykfd0TuENIw5nl7N5y5377W+b8c6ZKUD4FrYdugnBZmB fLlMd6qwHUy63asYWGLaP7/DCHuF0Py0gR1R+GSFwBWrISC3IevDClInqv9FRzJjF+HC jC21+wNVpR8cx4+B12Pgc5YkokgXiq9MrlGLvh84vueOd0Ol50BxNRch3OxHRuEkXBP6 m6kiT+OdVF71K1hzPttYQWMre+cv4qHeeIYr16KeAoDjjtYoM70sgSxfz0+1aquVKsWt v1pAnDL0oljDz9aVfkh/A8uFzzN0OEXXS/nrqGfTRKh9q0AsrrJNqf3vZz5HrCoQ43RW GLzg== X-Received: by 10.68.88.196 with SMTP id bi4mr80701694pbb.130.1427910792792; Wed, 01 Apr 2015 10:53:12 -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 id2sm2741653pbb.56.2015.04.01.10.53.11 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 01 Apr 2015 10:53:11 -0700 (PDT) From: Todd Previte To: tprevite@gmail.com Subject: [PATCH 1/5] drm/i915: Fix for DP CTS test 4.2.2.5 - I2C DEFER handling Date: Wed, 1 Apr 2015 10:52:58 -0700 Message-Id: <1427910782-19424-1-git-send-email-tprevite@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1427822106-29617-7-git-send-email-tprevite@gmail.com> References: <1427822106-29617-7-git-send-email-tprevite@gmail.com> Cc: dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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;