From patchwork Mon Jul 16 18:14:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Ciobanu X-Patchwork-Id: 10527455 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 24B5D60348 for ; Mon, 16 Jul 2018 18:22:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A67328DCB for ; Mon, 16 Jul 2018 18:22:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 18A1D28E81; Mon, 16 Jul 2018 18:22:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id BF63F28F33 for ; Mon, 16 Jul 2018 18:22:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A059F6E55D; Mon, 16 Jul 2018 18:22:19 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 301EA6E55D for ; Mon, 16 Jul 2018 18:22:18 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Jul 2018 11:22:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,362,1526367600"; d="scan'208";a="55439515" Received: from nc-new.jf.intel.com (HELO linux.intel.com) ([10.54.75.147]) by fmsmga008.fm.intel.com with SMTP; 16 Jul 2018 11:22:06 -0700 Received: by linux.intel.com (sSMTP sendmail emulation); Mon, 16 Jul 2018 11:14:54 -0700 From: Nathan Ciobanu To: intel-gfx@lists.freedesktop.org Date: Mon, 16 Jul 2018 11:14:45 -0700 Message-Id: <1531764885-18185-1-git-send-email-nathan.d.ciobanu@linux.intel.com> X-Mailer: git-send-email 2.7.4 Subject: [Intel-gfx] [PATCH v3] drm/i915/dp: Give up link training clock recovery after 10 failed attempts X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: marc.herbert@intel.com, dhinakaran.pandiyan@intel.com, rodrigo.vivi@intel.com MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Limit the link training clock recovery loop to 10 failed attempts at LANEx_CR_DONE per DP 1.4 spec section 3.5.1.2.2. Some USB-C MST hubs cause us to get stuck in this loop indefinitely requesting voltage swing: 0, pre-emphasis level: 2 voltage swing: 1, pre-emphasis level: 2 voltage swing: 0, pre-emphasis level: 3 over and over: max_vswing is never reached, drm_dp_clock_recovery_ok() never returns true and voltage_tries always gets reset to 1. The driver sends those values to the hub but the hub keeps requesting new values every time in the pattern shown above. Changes in v2: - updated commit message (DK, Manasi) - defined DP_DP14_MAX_CR_TRIES (Marc) - made the loop iterate for max 10 times (Rodrigo, Marc) Changes in v3: - changed error message to use DP_DP14_MAX_CR_TRIES Signed-off-by: Nathan Ciobanu --- drivers/gpu/drm/i915/intel_dp_link_training.c | 7 +++++-- include/drm/drm_dp_helper.h | 1 + 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c index 4da6e33c7fa1..4bfba65c431c 100644 --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -129,7 +129,7 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp) intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) { uint8_t voltage; - int voltage_tries, max_vswing_tries; + int voltage_tries, max_vswing_tries, cr_tries; uint8_t link_config[2]; uint8_t link_bw, rate_select; @@ -172,7 +172,7 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp) voltage_tries = 1; max_vswing_tries = 0; - for (;;) { + for (cr_tries = 0; cr_tries < DP_DP14_MAX_CR_TRIES; ++cr_tries) { uint8_t link_status[DP_LINK_STATUS_SIZE]; drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd); @@ -216,6 +216,9 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp) ++max_vswing_tries; } + DRM_ERROR("Failed clock recovery %d times, giving up!\n", + DP_DP14_MAX_CR_TRIES); + return false; } /* diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index c01564991a9f..2303ad8ed24e 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -820,6 +820,7 @@ #define DP_DP13_DPCD_REV 0x2200 #define DP_DP13_MAX_LINK_RATE 0x2201 +#define DP_DP14_MAX_CR_TRIES 10 #define DP_DPRX_FEATURE_ENUMERATION_LIST 0x2210 /* DP 1.3 */ # define DP_GTC_CAP (1 << 0) /* DP 1.3 */