From patchwork Mon Feb 8 15:01:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 379139 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=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 DD19CC433E0 for ; Mon, 8 Feb 2021 15:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93B7664E50 for ; Mon, 8 Feb 2021 15:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233943AbhBHPcA (ORCPT ); Mon, 8 Feb 2021 10:32:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:36400 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233105AbhBHP07 (ORCPT ); Mon, 8 Feb 2021 10:26:59 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 85FC164EFA; Mon, 8 Feb 2021 15:15:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612797349; bh=WW71G7RIySAXrZ8w22mOhxvua5JhQmPYzLZ3M1tSoA8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=na3KUVrj50CMEExkgH5aagTrsplUKs22sRs6ATkAAgvmc2QRBMvExtucml5oxrZq3 qEVYveCi5+krKNMPd3UE8btO7RC+cn1i88229HdHSfLbrdVp4o9Cf6TD/gtNCygKnA NaaNnl1sJwkXJ2YWb7CymXKHpGV/oSBwYfenRwYE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lyude Paul , Ville Syrjala , Imre Deak , Jani Nikula Subject: [PATCH 5.10 079/120] drm/i915: Fix the MST PBN divider calculation Date: Mon, 8 Feb 2021 16:01:06 +0100 Message-Id: <20210208145821.553572226@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145818.395353822@linuxfoundation.org> References: <20210208145818.395353822@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Imre Deak commit 882554042d138dbc6fb1a43017d0b9c3b38ee5f5 upstream. 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 Syrjala Link: https://patchwork.freedesktop.org/patch/msgid/20210125173636.1733812-2-imre.deak@intel.com (cherry picked from commit b59c27cab257cfbff939615a87b72bce83925710) Signed-off-by: Jani Nikula Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/display/intel_dp_mst.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- 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_con 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)