From patchwork Mon Jan 25 17:36:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 370552 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5ABFC433E0 for ; Mon, 25 Jan 2021 17:38:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB573221E5 for ; Mon, 25 Jan 2021 17:38:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731076AbhAYRh6 (ORCPT ); Mon, 25 Jan 2021 12:37:58 -0500 Received: from mga18.intel.com ([134.134.136.126]:23216 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731166AbhAYRh3 (ORCPT ); Mon, 25 Jan 2021 12:37:29 -0500 IronPort-SDR: OXq48ZPVpswbgiqWwyPCnNHuy7Foxo8XbUhLm8MeIhCgDonJr/IIxI1Uz8Tis2NoR2nMx+KVTI c3CqiLUBCmtw== X-IronPort-AV: E=McAfee;i="6000,8403,9875"; a="167443706" X-IronPort-AV: E=Sophos;i="5.79,374,1602572400"; d="scan'208";a="167443706" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2021 09:36:41 -0800 IronPort-SDR: SS+t5iJRs09DMk6QYOyzzfYVPVmMxIXKqlKZ7nzHO6kZmW7Y3RpzamfrzdWD/tM1xxIZ4va1pL quJEHqucNfFg== X-IronPort-AV: E=Sophos;i="5.79,374,1602572400"; d="scan'208";a="368762541" Received: from ideak-desk.fi.intel.com ([10.237.68.141]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2021 09:36:40 -0800 From: Imre Deak To: intel-gfx@lists.freedesktop.org Cc: Lyude Paul , Ville Syrjala , stable@vger.kernel.org Subject: [PATCH 2/2] drm/i915: Fix the MST PBN divider calculation Date: Mon, 25 Jan 2021 19:36:36 +0200 Message-Id: <20210125173636.1733812-2-imre.deak@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210125173636.1733812-1-imre.deak@intel.com> References: <20210125173636.1733812-1-imre.deak@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Atm the driver will calculate a wrong MST timeslots/MTP (aka time unit) value for MST streams if the link parameters (link rate or lane count) are limited in a way independent of the sink capabilities (reported by DPCD). One example of such a limitation is when a MUX between the sink and source connects only a limited number of lanes to the display and connects the rest of the lanes to other peripherals (USB). Another issue is that atm MST core calculates the divider based on the backwards compatible DPCD (at address 0x0000) vs. the extended capability info (at address 0x2200). This can result in leaving some part of the MST BW unused (For instance in case of the WD19TB dock). Fix the above two issues by calculating the PBN divider value based on the rate and lane count link parameters that the driver uses for all other computation. Bugzilla: https://gitlab.freedesktop.org/drm/intel/-/issues/2977 Cc: Lyude Paul Cc: Ville Syrjala Cc: Signed-off-by: Imre Deak Reviewed-by: Ville Syrjälä --- drivers/gpu/drm/i915/display/intel_dp_mst.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c index d6a1b961a0e8..b4621ed0127e 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c @@ -68,7 +68,9 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder, slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr, connector->port, - crtc_state->pbn, 0); + crtc_state->pbn, + drm_dp_get_vc_payload_bw(crtc_state->port_clock, + crtc_state->lane_count)); if (slots == -EDEADLK) return slots; if (slots >= 0)