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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 5182AC5B572 for ; Wed, 19 Aug 2026 06:28:22 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D436910E069; Wed, 19 Aug 2026 06:28:21 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="WPqKhTky"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id DEB3E10E069 for ; Wed, 19 Aug 2026 06:27:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1787120861; x=1818656861; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=ZfRrDJPNXEYs8fejYE2O0q+Rtel6Sx6GjUC7Pt9mJAM=; b=WPqKhTkykWMbrtenO80hrgZUGZjhKdbxnsYHJOwSHg2L3Hgch8m73gdH +6le9F9Z6ukOF6xblgS3jrtjI87zvteRKSfQhLZ47ghNLVs3RiRol2V6i XW8BFoYF60H9tWEO2Sm7z7DygK9to0TOalp9vhgsybvk5Nceyosf4ki1k nhtulwPvw2pJCqClEvd3W/EfUhJ3FZZHArVUu8dIMC2INyNGNjJJPIi+r HIgzvWwb7fG6X0aa+QjkMGM+3EiRkeWj4l4kN7ooo6LqnSY4bXk22yMko C+stXJ2hqLQ+t6WVchx4LWZia5f+LoVesUCnvWoxKgHJuNDcEKkZbXpVR w==; X-CSE-ConnectionGUID: izrNL/edT3GkQc4Hd3jgsg== X-CSE-MsgGUID: EVNHLGJSRTy02a4RVRtX5g== X-IronPort-AV: E=McAfee;i="6800,10657,11879"; a="87641679" X-IronPort-AV: E=Sophos;i="6.25,231,1779174000"; d="scan'208";a="87641679" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 23:27:40 -0700 X-CSE-ConnectionGUID: occ319hNQ56QSAGxLPpHuQ== X-CSE-MsgGUID: DjBSzltCSs+jQdwFyeKWmA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,231,1779174000"; d="scan'208";a="264132511" Received: from sowmi-x299-aorus-gaming-3-pro.iind.intel.com ([10.223.74.56]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 23:27:39 -0700 From: Sowmiya S To: igt-dev@lists.freedesktop.org Cc: karthik.b.s@intel.com, kunal1.joshi@intel.com, Sowmiya S Subject: [PATCH i-g-t v6 0/3] kms_dp_linktrain_fallback: Add UHBR-to-HBR fallback subtest Date: Wed, 19 Aug 2026 11:57:27 +0530 Message-ID: <20260819062730.1116813-1-sowmiya.s@intel.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: igt-dev@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development mailing list for IGT GPU Tools List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: igt-dev-bounces@lists.freedesktop.org Sender: "igt-dev" DP 2.x links use 128b/132b channel encoding for UHBR rates (UHBR10/13.5/20) and 8b/10b for legacy HBR3 and below. The transition between the two encodings goes through a port-slice reset on the source side. The existing dp-fallback subtest only covers 8b/10b-to-8b/10b fallback; this series adds a dedicated subtest for the UHBR->HBR direction. Adds two library helpers to lib/i915/i915_dp: - i915_dp_is_uhbr_rate(): mirrors the kernel's drm_dp_is_uhbr_rate() - i915_dp_get_next_lower_rate(): parses the force_link_rate debugfs list with proper strtok_r/strtol/errno handling const char * signature for i915_dp_set_link_params() so string literals can be passed directly without a writable-array workaround. Fixes a pre-existing bug where the file-static traversed_mst_output_count was never reset between subtests, causing all MST outputs to be silently skipped as "already visited" in a full-binary run. Adds the uhbr-to-hbr-fallback subtest. The subtest pins the link at the highest sustainable UHBR rate (stepping down if the cable cannot sustain the sink's max), forces repeated LT_FAILURE_REDUCED_CAPS failures, and asserts the rate drops below UHBR10. MST topologies are supported since all siblings share the physical link. The existing run_lt_fallback_test() is extended with force_uhbr parameter to avoid ~45 lines of duplication. v2: Resets MST traversal state per test run v3: - Drop "exercising the port slice reset path" from SUBTEST description - Revert unrelated cosmetic hunk in setup_mst_outputs() - Single UHBR capability gate using i915_dp_get_max_link_rate() - remove duplicate gate using i915_dp_get_max_supported_rate() - Fix link rate log units (10 kbit/s, not kbps) - Add igt_reset_connectors() to pin-loop early-return path - Replace UHBR10_LINK_RATE define with i915_dp_is_uhbr_rate() helper - Replace open-coded strtok() parsing with i915_dp_get_next_lower_rate() - Hard-assert "fallback not reached" instead of returning false - Remove dead traversed_mst_output_count reset in run_dsc path - Merge run_uhbr_to_hbr_fallback_test() into run_lt_fallback_test() - Use "auto" string literal directly (const char * param fix) - Move reset before UHBR capability gate read in run_lt_fallback_test() - Document force_uhbr parameter and "clear the pin" reset behaviour v4: - name the UHBR10 threshold and make i915_dp_is_uhbr_rate() a static inline in the header to avoid a cross-TU call - parse intel_dp_allowed_link_configs instead of the source-only i915_dp_force_link_rate list in i915_dp_get_next_lower_rate() - avoid the implicit long to int narrowing on the return value v5: commit display reset before fallback v6: Fold patch 4 to 3 Sowmiya S (3): lib/i915/i915_dp: Add UHBR helpers and const-correct set_link_params tests/intel/kms_dp_linktrain_fallback: Reset traversed MST output count tests/intel/kms_dp_linktrain_fallback: Add UHBR-to-HBR fallback subtest lib/i915/i915_dp.c | 58 ++++++- lib/i915/i915_dp.h | 24 ++- tests/intel/kms_dp_linktrain_fallback.c | 202 +++++++++++++++++++++--- 3 files changed, 260 insertions(+), 24 deletions(-) -- 2.43.0