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 X-Spam-Level: X-Spam-Status: No, score=-13.7 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 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 1AEE8C433DB for ; Mon, 22 Feb 2021 17:11:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB7C064E77 for ; Mon, 22 Feb 2021 17:11:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230174AbhBVRLM (ORCPT ); Mon, 22 Feb 2021 12:11:12 -0500 Received: from mga07.intel.com ([134.134.136.100]:56929 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230379AbhBVRLK (ORCPT ); Mon, 22 Feb 2021 12:11:10 -0500 IronPort-SDR: 9pR3esMLp2LlqjdIqeJEwp4d+xTwirV3gfxwZkCiEwoXTJO7fE6efGWMiaX64wavi6Lxw1rMYL P0MYw/55pWfQ== X-IronPort-AV: E=McAfee;i="6000,8403,9903"; a="248571524" X-IronPort-AV: E=Sophos;i="5.81,197,1610438400"; d="scan'208";a="248571524" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2021 09:09:23 -0800 IronPort-SDR: UYI7pOe9Ti6xsV+k3UgqhFluHEF2aBqgzG3+W/lVv8zdILt6R50KGVyaxpY835NCtl1WQHDFg+ Ps+75/XmkjGg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,197,1610438400"; d="scan'208";a="402689444" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.171]) by orsmga008.jf.intel.com with SMTP; 22 Feb 2021 09:09:18 -0800 Received: by stinkbox (sSMTP sendmail emulation); Mon, 22 Feb 2021 19:09:17 +0200 Date: Mon, 22 Feb 2021 19:09:17 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Wayne Lin Cc: eryk.brol@amd.com, qingqing.zhuo@amd.com, stable@vger.kernel.org, jerry.zuo@amd.com, dri-devel@lists.freedesktop.org, Nicholas.Kazlauskas@amd.com Subject: Re: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr Message-ID: References: <20210222040027.23505-1-Wayne.Lin@amd.com> <20210222040027.23505-2-Wayne.Lin@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Patchwork-Hint: comment Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Feb 22, 2021 at 07:02:03PM +0200, Ville Syrjälä wrote: > On Mon, Feb 22, 2021 at 12:00:26PM +0800, Wayne Lin wrote: > > [Why & How] > > According to DP spec, broadcast message LCT equals to 1 and LCR equals > > to 6. Current implementation is incorrect. Fix it. > > > > Signed-off-by: Wayne Lin > > Cc: stable@vger.kernel.org > > --- > > drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c > > index 17dbed0a9800..713ef3b42054 100644 > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > > @@ -2727,8 +2727,14 @@ static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr, > > else > > hdr->broadcast = 0; > > hdr->path_msg = txmsg->path_msg; > > - hdr->lct = mstb->lct; > > - hdr->lcr = mstb->lct - 1; > > + if (hdr->broadcast) { > > + hdr->lct = 1; > > + hdr->lcr = 6; > > + } else { > > + hdr->lct = mstb->lct; > > + hdr->lcr = mstb->lct - 1; > > + } > > + > > if (mstb->lct > 1) > > memcpy(hdr->rad, mstb->rad, mstb->lct / 2); > > We should also do something about RAD no? Just skip the RAD stuff by s/mstb->lct/hdr->lct/ here I guess? -- Ville Syrjälä Intel