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 57B44C79F89 for ; Mon, 7 Sep 2026 04:41:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C834310E61F; Mon, 7 Sep 2026 04:41:52 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="mOZ+o7pV"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id E6F0F10E5DD for ; Mon, 7 Sep 2026 04:41:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1788756111; x=1820292111; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=pioSbD2s/+M7BbkAj2hC03O9yt2dCo68AHfkzH+u+vk=; b=mOZ+o7pV7gY3JVaxWDvozGk/JxGZ+XHAya3SgqCd36U3voEUmMqtcRLS MIbuka/217YkIvHs3TKU+28mBtCLl9nQc/xyygUTa+AFC4ug7yC7aMr+B fAE2Xp1OWYv7eI2blFq7mhxJC4SqWhCacG06rh+aZDhVub1UGLKg5usxR YoVeesfcUDdg8qNziVrzv21xkDC5v+7rThNbqdO7NGYbLZFslo2hsTtgS k208X4kbZicnDOMB011dW6pdAMTvVnSoBH05QTYzqqeHBqfOTsdvU5lHh dVH9V0s7QuYHlW2V63YHRvxrARRVwY6BWfeYp9PNX7cxHOdOrG4ldjrUA g==; X-CSE-ConnectionGUID: xJOZ4WaHSFmt+gn6mRj9aw== X-CSE-MsgGUID: JbBHj7wDSWi/lTcPEwWYDg== X-IronPort-AV: E=McAfee;i="6800,10657,11898"; a="89205882" X-IronPort-AV: E=Sophos;i="6.25,266,1779174000"; d="scan'208";a="89205882" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Sep 2026 21:41:50 -0700 X-CSE-ConnectionGUID: aD22GvyuQo6BOeVXhRG22A== X-CSE-MsgGUID: 4Uftw5kGQlqaKCHsXlZ0jg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,266,1779174000"; d="scan'208";a="264409734" Received: from xiaolu.sh.intel.com ([10.239.146.103]) by fmviesa009.fm.intel.com with ESMTP; 06 Sep 2026 21:41:48 -0700 From: Xiao Lu To: intel-gfx@lists.freedesktop.org Cc: jani.nikula@linux.intel.com, ville.syrjala@linux.intel.com, imre.deak@intel.com, ankit.k.nautiyal@intel.com, Xiao Lu Subject: [PATCH v5 1/2] drm/dp/mst: recognize DP-to-HDMI PCON as virtual DPCD in DP-to-DP topology Date: Mon, 7 Sep 2026 12:39:21 +0800 Message-ID: <20260907043922.1367673-1-xiaolu.xie@intel.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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" drm_dp_mst_is_virtual_dpcd() checks if a branch port qualifies as a virtual DPCD device by looking for a downstream port with Peer_Device_Type=3 (DP_PEER_DEVICE_SST_SINK). Some PCON devices advertise their downstream HDMI sink port using Peer_Device_Type=4 (DP_PEER_DEVICE_DP_LEGACY_CONV) with a non-zero DPCD_Revision in the link address reply, indicating a virtual DPCD is present (VESA SCR Option 2). The current check misses this case, so passthrough_aux is never set and DSC passthrough modes are rejected. Accept DP_PEER_DEVICE_DP_LEGACY_CONV as a valid downstream peer type in the DP-to-DP branch so these PCON topologies are correctly identified. Signed-off-by: Xiao Lu --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 4de36fda0..7d1128bcd 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -6045,7 +6045,8 @@ static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port) port->mstb && port->mstb->num_ports == 2) { list_for_each_entry(downstream_port, &port->mstb->ports, next) { - if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK && + if ((downstream_port->pdt == DP_PEER_DEVICE_SST_SINK || + downstream_port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV) && !downstream_port->input) { mutex_unlock(&port->mgr->lock); return true; -- 2.43.0