From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07912C433DB for ; Tue, 16 Mar 2021 16:54:33 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A9BD165090 for ; Tue, 16 Mar 2021 16:54:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9BD165090 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3624F891CA; Tue, 16 Mar 2021 16:54:32 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 28C6F891CA for ; Tue, 16 Mar 2021 16:54:31 +0000 (UTC) IronPort-SDR: RjBONRjDCP4hZ64vBvmgyzjXgVc2PbKTJk6sXl6B4VCLj3ylSsfuVWy0xzSJWjY6s7tn0R0nHI ugGEW/S+YTnw== X-IronPort-AV: E=McAfee;i="6000,8403,9925"; a="188653924" X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="188653924" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 09:54:30 -0700 IronPort-SDR: 0hjODpLVOHeyZ/cVn6yvpHGdTVvurvZna/zWeemXXG2a6AUwfo/dVfB1a3Mocfp0Y1eYz028dg 9LF4imo3rlfQ== X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="388526404" Received: from ideak-desk.fi.intel.com ([10.237.68.141]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 09:54:28 -0700 From: Imre Deak To: intel-gfx@lists.freedesktop.org Date: Tue, 16 Mar 2021 18:54:26 +0200 Message-Id: <20210316165426.3388513-1-imre.deak@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915/ilk-glk: Fix link training on links with LTTPRs X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Takashi Iwai , stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The spec requires to use at least 3.2ms for the AUX timeout period if there are LT-tunable PHY Repeaters on the link (2.11.2). An upcoming spec update makes this more specific, by requiring a 3.2ms minimum timeout period for the LTTPR detection reading the 0xF0000-0xF0007 range (3.6.5.1). Accordingly disable LTTPR detection until GLK, where the maximum timeout we can set is only 1.6ms. Link training in the non-transparent mode is known to fail at least on some SKL systems with a WD19 dock on the link, which exposes an LTTPR (see the References below). While this could have different reasons besides the too short AUX timeout used, not detecting LTTPRs (and so not using the non-transparent LT mode) fixes link training on these systems. While at it add a code comment about the platform specific maximum timeout values. Reported-by: Takashi Iwai References: https://gitlab.freedesktop.org/drm/intel/-/issues/3166 Fixes: b30edfd8d0b4 ("drm/i915: Switch to LTTPR non-transparent mode link training") Cc: # v5.11 Cc: Takashi Iwai Signed-off-by: Imre Deak --- drivers/gpu/drm/i915/display/intel_dp_aux.c | 7 +++++++ drivers/gpu/drm/i915/display/intel_dp_link_training.c | 8 ++++++++ 2 files changed, 15 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c index eaebf123310a..b581e8acce07 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c @@ -133,6 +133,7 @@ static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp, else precharge = 5; + /* Max timeout value on ILK-BDW: 1.6ms */ if (IS_BROADWELL(dev_priv)) timeout = DP_AUX_CH_CTL_TIME_OUT_600us; else @@ -159,6 +160,12 @@ static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp, enum phy phy = intel_port_to_phy(i915, dig_port->base.port); u32 ret; + /* + * Max timeout values: + * SKL-GLK: 1.6ms + * CNL: 3.2ms + * ICL+: 4ms + */ ret = DP_AUX_CH_CTL_SEND_BUSY | DP_AUX_CH_CTL_DONE | DP_AUX_CH_CTL_INTERRUPT | diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c index 19ba7c7cbaab..de6d70a29b47 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c @@ -123,10 +123,18 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable) */ int intel_dp_lttpr_init(struct intel_dp *intel_dp) { + struct drm_i915_private *i915 = dp_to_i915(intel_dp); int lttpr_count; bool ret; int i; + /* + * Detecting LTTPRs must be avoided on platforms with an AUX timeout + * period < 3.2ms. (see DP Standard v2.0, 2.11.2, 3.6.6.1). + */ + if (INTEL_GEN(i915) < 10) + return 0; + if (intel_dp_is_edp(intel_dp)) return 0; -- 2.25.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx