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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4A2FC433F5 for ; Mon, 18 Oct 2021 09:42:08 +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 7605A60EB4 for ; Mon, 18 Oct 2021 09:42:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7605A60EB4 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 549B96E9C2; Mon, 18 Oct 2021 09:42:06 +0000 (UTC) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9F6386E9C1 for ; Mon, 18 Oct 2021 09:42:03 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10140"; a="228092158" X-IronPort-AV: E=Sophos;i="5.85,381,1624345200"; d="scan'208";a="228092158" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2021 02:42:03 -0700 X-IronPort-AV: E=Sophos;i="5.85,381,1624345200"; d="scan'208";a="493516730" Received: from ideak-desk.fi.intel.com ([10.237.68.141]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2021 02:42:02 -0700 From: Imre Deak To: intel-gfx@lists.freedesktop.org Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , stable@vger.kernel.org Date: Mon, 18 Oct 2021 12:41:51 +0300 Message-Id: <20211018094154.1407705-4-imre.deak@intel.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211018094154.1407705-1-imre.deak@intel.com> References: <20211018094154.1407705-1-imre.deak@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Intel-gfx] [PATCH 3/6] drm/i915/dp: Ensure max link params are always valid 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" Atm until the DPCD for a connector is read the max link rate and lane count params are invalid. If the connector is modeset, in intel_dp_compute_config(), intel_dp_common_len_rate_limit(max_link_rate) will return 0, leading to a intel_dp->common_rates[-1] access. Fix the above by making sure the max link params are always valid. The above access leads to an undefined behaviour by definition, though not causing a user visible problem to my best knowledge, see the previous patch why. Nevertheless it is an undefined behaviour and it triggers a BUG() in CONFIG_UBSAN builds, hence CC:stable. Cc: Ville Syrjälä Cc: Signed-off-by: Imre Deak --- drivers/gpu/drm/i915/display/intel_dp.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 153ae944a354b..1935eb49f9574 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -1864,6 +1864,12 @@ void intel_dp_set_link_params(struct intel_dp *intel_dp, intel_dp->lane_count = lane_count; } +static void intel_dp_reset_max_link_params(struct intel_dp *intel_dp) +{ + intel_dp->max_link_lane_count = intel_dp_max_common_lane_count(intel_dp); + intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp); +} + /* Enable backlight PWM and backlight PP control. */ void intel_edp_backlight_on(const struct intel_crtc_state *crtc_state, const struct drm_connector_state *conn_state) @@ -2023,8 +2029,7 @@ void intel_dp_sync_state(struct intel_encoder *encoder, if (intel_dp->dpcd[DP_DPCD_REV] == 0) intel_dp_get_dpcd(intel_dp); - intel_dp->max_link_lane_count = intel_dp_max_common_lane_count(intel_dp); - intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp); + intel_dp_reset_max_link_params(intel_dp); } bool intel_dp_initial_fastset_check(struct intel_encoder *encoder, @@ -2597,6 +2602,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp) intel_dp_set_sink_rates(intel_dp); intel_dp_set_common_rates(intel_dp); + intel_dp_reset_max_link_params(intel_dp); /* Read the eDP DSC DPCD registers */ if (DISPLAY_VER(dev_priv) >= 10) @@ -4338,12 +4344,7 @@ intel_dp_detect(struct drm_connector *connector, * supports link training fallback params. */ if (intel_dp->reset_link_params || intel_dp->is_mst) { - /* Initial max link lane count */ - intel_dp->max_link_lane_count = intel_dp_max_common_lane_count(intel_dp); - - /* Initial max link rate */ - intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp); - + intel_dp_reset_max_link_params(intel_dp); intel_dp->reset_link_params = false; } @@ -5011,6 +5012,7 @@ intel_dp_init_connector(struct intel_digital_port *dig_port, intel_dp_set_source_rates(intel_dp); intel_dp_set_default_sink_rates(intel_dp); intel_dp_set_common_rates(intel_dp); + intel_dp_reset_max_link_params(intel_dp); if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) intel_dp->pps.active_pipe = vlv_active_pipe(intel_dp); -- 2.27.0