From patchwork Mon Aug 21 21:03:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: jim.bride@linux.intel.com X-Patchwork-Id: 9913793 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 B0ACD603FA for ; Mon, 21 Aug 2017 21:06:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98F042873F for ; Mon, 21 Aug 2017 21:06:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8D3FE287C3; Mon, 21 Aug 2017 21:06:28 +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=-4.2 required=2.0 tests=BAYES_00, 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 0F6672873F for ; Mon, 21 Aug 2017 21:06:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 25DEA89C59; Mon, 21 Aug 2017 21:06:27 +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 43ECB89C59 for ; Mon, 21 Aug 2017 21:06:25 +0000 (UTC) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga105.jf.intel.com with ESMTP; 21 Aug 2017 14:06:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,409,1498546800"; d="scan'208";a="142323139" Received: from shiv.jf.intel.com ([10.54.75.141]) by fmsmga005.fm.intel.com with ESMTP; 21 Aug 2017 14:06:20 -0700 From: Jim Bride To: intel-gfx@lists.freedesktop.org Date: Mon, 21 Aug 2017 14:03:36 -0700 Message-Id: <1503349416-29151-1-git-send-email-jim.bride@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1502313667-18127-1-git-send-email-jim.bride@linux.intel.com> References: <1502313667-18127-1-git-send-email-jim.bride@linux.intel.com> Cc: Paulo Zanoni , Jani Nikula , Rodrigo Vivi Subject: [Intel-gfx] [PATCH v6] drm/i915/edp: Be less aggressive about changing link config on eDP 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-Virus-Scanned: ClamAV using ClamSMTP This set of changes has some history to them. There were several attempts to add what was called "fast link training" to i915, which actually wasn't fast link training as per the DP spec. These changes were: commit 5fa836a9d859 ("drm/i915: DP link training optimization") commit 4e96c97742f4 ("drm/i915: eDP link training optimization") which were eventually hand-reverted by: commit 34511dce4b35 ("drm/i915: Revert DisplayPort fast link training feature") in kernel 4.7-rc4. The eDP pieces of the above revert, however, had some very bad side-effects on PSR functionality on Skylake. The issue at hand is that when PSR exits i915 briefly emits TP1 followed by TP2/3 (depending on the original link configuration) in order to quickly get the source and sink back in synchronization across the link before handing control back to the i915. There's an assumption that none of the link configuration information has changed (and thus it's still valid) since the last full link training operation. The revert above was identified via a bisect as the cause of some of Skylake's PSR woes. This patch, largely based on commit 4e96c97742f4 ("drm/i915: eDP link training optimization") puts the eDP portions of this patch back in place. None of the flickering issues that spurred the revert have been seen, and I suspect the real culprits here were addressed by some of the recent link training changes that Manasi has implemented, and PSR on Skylake is definitely more happy with these changes in-place. v2 and v3: Rebase v4: * Clean up accesses to train_set_valid a bit for easier reading. (Chris) * Rebase v5: * Checkpatch cleanup * Rebase v6: * is_edp() => intel_dp_is_edp() * rebase Cc: Chris Wilson Cc: Rodrigo Vivi Cc: Paulo Zanoni Cc: Manasi D Navare Cc: Mika Kahola Cc: Jani Nikula Fixes: 34511dce4 ("drm/i915: Revert DisplayPort fast link training feature") Signed-off-by: Jim Bride --- drivers/gpu/drm/i915/intel_dp.c | 2 ++ drivers/gpu/drm/i915/intel_dp_link_training.c | 15 ++++++++++++++- drivers/gpu/drm/i915/intel_drv.h | 2 ++ 3 files changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index e385658..38bc7e0 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4750,6 +4750,7 @@ intel_dp_long_pulse(struct intel_connector *intel_connector) intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp); intel_dp->reset_link_params = false; + intel_dp->train_set_valid = false; } intel_dp_print_rates(intel_dp); @@ -6019,6 +6020,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port, intel_dp_set_source_rates(intel_dp); intel_dp->reset_link_params = true; + intel_dp->train_set_valid = false; intel_dp->pps_pipe = INVALID_PIPE; intel_dp->active_pipe = INVALID_PIPE; diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c index 05907fa..79fe369 100644 --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -94,7 +94,8 @@ static bool intel_dp_reset_link_train(struct intel_dp *intel_dp, uint8_t dp_train_pat) { - memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set)); + if (!intel_dp->train_set_valid) + memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set)); intel_dp_set_signal_levels(intel_dp); return intel_dp_set_link_train(intel_dp, dp_train_pat); } @@ -162,9 +163,18 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) DP_TRAINING_PATTERN_1 | DP_LINK_SCRAMBLING_DISABLE)) { DRM_ERROR("failed to enable link training\n"); + intel_dp->train_set_valid = false; return false; } + /* + * The initial set of link parameters are set by this point, so go + * ahead and set intel_dp->train_set_valid to false in case any of + * the succeeding steps fail. It will be set back to true if we were + * able to achieve clock recovery in the specified configuration. + */ + intel_dp->train_set_valid = false; + voltage_tries = 1; max_vswing_tries = 0; for (;;) { @@ -179,6 +189,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) { DRM_DEBUG_KMS("clock recovery OK\n"); + intel_dp->train_set_valid = intel_dp_is_edp(intel_dp); return true; } @@ -256,6 +267,7 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp) training_pattern | DP_LINK_SCRAMBLING_DISABLE)) { DRM_ERROR("failed to start channel equalization\n"); + intel_dp->train_set_valid = false; return false; } @@ -296,6 +308,7 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp) /* Try 5 times, else fail and try at lower BW */ if (tries == 5) { intel_dp_dump_link_status(link_status); + intel_dp->train_set_valid = false; DRM_DEBUG_KMS("Channel equalization failed 5 times\n"); } diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 2940d39..891c892 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -995,6 +995,7 @@ struct intel_dp { struct drm_dp_aux aux; enum intel_display_power_domain aux_power_domain; uint8_t train_set[4]; + bool train_set_valid; int panel_power_up_delay; int panel_power_down_delay; int panel_power_cycle_delay; @@ -1549,6 +1550,7 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count) } bool intel_dp_read_dpcd(struct intel_dp *intel_dp); +bool is_edp(struct intel_dp *intel_dp); int intel_dp_link_required(int pixel_clock, int bpp); int intel_dp_max_data_rate(int max_link_clock, int max_lanes); bool intel_digital_port_connected(struct drm_i915_private *dev_priv,