From patchwork Thu Oct 7 10:57:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jani Nikula X-Patchwork-Id: 12541549 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03AF9C433F5 for ; Thu, 7 Oct 2021 10:57:36 +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 BCC4260F58 for ; Thu, 7 Oct 2021 10:57:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BCC4260F58 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4DA1A6F400; Thu, 7 Oct 2021 10:57:35 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3D5986F400 for ; Thu, 7 Oct 2021 10:57:34 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10129"; a="226173004" X-IronPort-AV: E=Sophos;i="5.85,354,1624345200"; d="scan'208";a="226173004" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2021 03:57:33 -0700 X-IronPort-AV: E=Sophos;i="5.85,354,1624345200"; d="scan'208";a="478518554" Received: from roliveir-mobl1.ger.corp.intel.com (HELO localhost) ([10.249.41.10]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2021 03:57:31 -0700 From: Jani Nikula To: intel-gfx@lists.freedesktop.org Cc: jani.nikula@intel.com, =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= Date: Thu, 7 Oct 2021 13:57:27 +0300 Message-Id: <20211007105727.18439-1-jani.nikula@intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Subject: [Intel-gfx] [PATCH] drm/i915/dp: take LTTPR into account in 128b/132b rates 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Limit the supported UHBR rates based on the repeater support, if there are repeaters. This should be done in DP helper level, but that requires an overhaul of the LTTPR handling, as the max rate is not enough to represent how 128b/132b rates may be masked along the way. Curiously, the spec says: * Shall be cleared to 00h when operating in 8b/10b Link Layer. * Each LTTPR on the way back to the DPTX shall clear the bits that do not correspond to the LTTPR's current bit rate. It's rather vague if we can reliably use the field at this time due to the wording "operating" and "current". But it would seem bizarre to have to wait until trying to operate a 128b/132b link layer at a certain bit rate to figure this out. Cc: Ville Syrjälä Signed-off-by: Jani Nikula Reviewed-by: Ville Syrjälä --- drivers/gpu/drm/i915/display/intel_dp.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 74a657ae131a..5824b7d9f4a8 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -140,6 +140,9 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp) return; } + /* + * Sink rates for 8b/10b. + */ max_rate = drm_dp_bw_code_to_link_rate(intel_dp->dpcd[DP_MAX_LINK_RATE]); max_lttpr_rate = drm_dp_lttpr_max_link_rate(intel_dp->lttpr_common_caps); if (max_lttpr_rate) @@ -163,6 +166,20 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp) drm_dp_dpcd_readb(&intel_dp->aux, DP_128B132B_SUPPORTED_LINK_RATES, &uhbr_rates); + if (drm_dp_lttpr_count(intel_dp->lttpr_common_caps)) { + /* We have a repeater */ + if (intel_dp->lttpr_common_caps[0] >= 0x20 && + intel_dp->lttpr_common_caps[DP_MAIN_LINK_CHANNEL_CODING_PHY_REPEATER - + DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV] & + DP_PHY_REPEATER_128B132B_SUPPORTED) { + /* Repeater supports 128b/132b, valid UHBR rates */ + uhbr_rates &= intel_dp->lttpr_common_caps[DP_PHY_REPEATER_128B132B_RATES - DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV]; + } else { + /* Does not support 128b/132b */ + uhbr_rates = 0; + } + } + if (uhbr_rates & DP_UHBR10) intel_dp->sink_rates[i++] = 1000000; if (uhbr_rates & DP_UHBR13_5)