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 17A5AC79F89 for ; Mon, 7 Sep 2026 04:53:40 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 73A4210E42D; Mon, 7 Sep 2026 04:53:40 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="f1EGHK3O"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 655CC10E42D for ; Mon, 7 Sep 2026 04:53:39 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 6BE4460052; Mon, 7 Sep 2026 04:53:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8CEA1F00A3D; Mon, 7 Sep 2026 04:53:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788756818; bh=WrnuYHkPNCA4tvCKgU+E38ZT1wstAO0xFwrbLCeHBCI=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=f1EGHK3OHn4Mnw9gKOZ2+I5ZZT78zPTAI8BV7reZFQ1K1upaJ1RCTbTnOzmQRViqj 2DEoj5IxYyWTaDfIIEK/wyYE8yhz5cq1dIAUpIaei8+s12egYqJIE9DQfH4wxxJJok tcCi2PeKQciHnKBaxrO7SDVkcq3EOQYUjQ/ZZmsynqe3cQ0CPf2UbQw74X7+EPMG38 U4TNdS6OB0AGxQk23RiFmVDVAuKpc6QBLpv6nEYyJBvThz5XueNdX+jmBQecg5gGVv aOff2+n93zlmas3OV1WfXwJ8VX9NBsNNExlgIhO509tCqZS1WvoavwzS48MUKmI7RL WtMYpHt4GeyAw== From: sashiko-bot@kernel.org Subject: Re: [PATCH v5 1/2] drm/dp/mst: recognize DP-to-HDMI PCON as virtual DPCD in DP-to-DP topology To: "Xiao Lu" Cc: intel-gfx@lists.freedesktop.org In-Reply-To: <20260907044140.1367870-1-xiaolu.xie@intel.com> References: <20260906094156.1057767-1-xiaolu.xie@intel.com> <20260907044140.1367870-1-xiaolu.xie@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 07 Sep 2026 04:53:37 +0000 Message-Id: <20260907045337.E8CEA1F00A3D@smtp.kernel.org> 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: , Reply-To: sashiko-reviews@lists.linux.dev Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] The logic for identifying a Virtual DPCD downstream port misses = the required DPCD_Revision check, causing standard legacy converters to be = incorrectly identified as Virtual DPCDs. -- commit 659313a54262ef8ae8960a7c3b7925da1958206b Author: Xiao Lu drm/dp/mst: recognize DP-to-HDMI PCON as virtual DPCD in DP-to-DP topol= ogy This commit updates drm_dp_mst_is_virtual_dpcd() to accept legacy converters as a valid downstream peer type. This allows the driver to correctly identi= fy PCON devices that advertise their downstream HDMI sink port using DP_PEER_DEVICE_DP_LEGACY_CONV. > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/= drm/display/drm_dp_mst_topology.c > index 7ce9e212770ad..5f15d9313a20e 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -6047,7 +6047,8 @@ static bool drm_dp_mst_is_virtual_dpcd(struct drm_d= p_mst_port *port) > port->mstb && > port->mstb->num_ports =3D=3D 2) { > list_for_each_entry(downstream_port, &port->mstb->ports, next) { > - if (downstream_port->pdt =3D=3D DP_PEER_DEVICE_SST_SINK && > + if ((downstream_port->pdt =3D=3D DP_PEER_DEVICE_SST_SINK || > + downstream_port->pdt =3D=3D DP_PEER_DEVICE_DP_LEGACY_CONV) && > !downstream_port->input) { > mutex_unlock(&port->mgr->lock); > return true; [Severity: Medium] Will this incorrectly identify standard legacy converters as Virtual DPCDs? The commit message notes that Virtual DPCD presence for legacy converters is indicated by a non-zero DPCD_Revision (VESA SCR Option 2), but the added logic accepts DP_PEER_DEVICE_DP_LEGACY_CONV without verifying if downstream_port->dpcd_rev !=3D 0. Could this cause the driver to improperly set passthrough_aux and attempt DPCD reads on a standard DP-to-VGA/DVI/HDMI converter (with dpcd_rev =3D=3D= 0) connected to a 2-port MST branch device, resulting in AUX timeouts or link training failures? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260907044140.1367= 870-1-xiaolu.xie@intel.com?part=3D1