From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 621EB328B47; Fri, 9 Jan 2026 14:19:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767968360; cv=none; b=IB74AvDwIOSz4jhXsNcH/or9uPcxvXhTrE1vvZ4TpU7SO/Hoa96y4NYHePijn04uL31g9tUvfSlOOA5yIYYU5n4O9lXk9oezSJ0BmL9PUYTuoSQhIKY5bLCelOEVn+TzjepZXlUKyJEc+uupyw+J6MRQdtX2jTVV1oQH7EtS4N0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767968360; c=relaxed/simple; bh=/JWENtIa2ovonoQrnpplxQr6BvOzWq5M7Qq+Ox+pkBM=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=te058dcasy5ZMZDl/MJkhB6179s48pRA1rn9vxleNiASAPn5xEvkUKtqYIgy5t2Y0eQirfV7mpxjus93JoAMt3aWcbdE4QC+EibgiLdJyd+/gBa80cQR5tdI0JewV4OLay67/fCCkJUjmCRRm1QgdbziA0ylrf9CGTU1rFvIWrA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.224.150]) by frasgout.his.huawei.com (SkyGuard) with ESMTPS id 4dnkRF5TMnzHnGcV; Fri, 9 Jan 2026 22:19:05 +0800 (CST) Received: from dubpeml100005.china.huawei.com (unknown [7.214.146.113]) by mail.maildlp.com (Postfix) with ESMTPS id F39AA40563; Fri, 9 Jan 2026 22:19:15 +0800 (CST) Received: from localhost (10.203.177.15) by dubpeml100005.china.huawei.com (7.214.146.113) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Fri, 9 Jan 2026 14:19:15 +0000 Date: Fri, 9 Jan 2026 14:19:13 +0000 From: Jonathan Cameron To: Robert Richter CC: Davidlohr Bueso , Dave Jiang , Alison Schofield , Vishal Verma , Ira Weiny , Dan Williams , , Subject: Re: [PATCH v3] cxl/port: Fix target list setup for multiple decoders sharing the same dport Message-ID: <20260109141913.0000523f@huawei.com> In-Reply-To: References: <20260108101324.509667-1-rrichter@amd.com> <20260108160835.0000092e@huawei.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500009.china.huawei.com (7.191.174.84) To dubpeml100005.china.huawei.com (7.214.146.113) On Fri, 9 Jan 2026 08:28:56 +0100 Robert Richter wrote: > On Thu, Jan 08, 2026 at 04:08:35PM +0000, Jonathan Cameron wrote: > > On Thu, 8 Jan 2026 11:13:23 +0100 > > Robert Richter wrote: > > > > > If a switch port has more than one decoder that is using the same > > > downstream port, the enumeration of the target lists may fail with: > > > > > > # dmesg | grep target.list > > > update_decoder_targets: cxl decoder1.0: dport3 found in target list, index 3 > > > update_decoder_targets: cxl decoder1.0: dport2 found in target list, index 2 > > > update_decoder_targets: cxl decoder1.0: dport0 found in target list, index 0 > > > update_decoder_targets: cxl decoder2.0: dport3 found in target list, index 1 > > > update_decoder_targets: cxl decoder4.0: dport3 found in target list, index 1 > > > cxl_mem mem6: failed to find endpoint12:0000:00:01.4 in target list of decoder2.1 > > > cxl_mem mem8: failed to find endpoint13:0000:20:01.4 in target list of decoder4.1 > > > > > > The case, that the same downstream port can be used in multiple target > > > lists, is allowed and possible. > > > > > > Fix the update of the target list. Enumerate all children of the > > > switch port and do not stop the iteration after the first matching > > > target was found. > > > > > > With the fix applied: > > > > > > # dmesg | grep target.list > > > update_decoder_targets: cxl decoder1.0: dport2 found in target list, index 2 > > > update_decoder_targets: cxl decoder1.0: dport0 found in target list, index 0 > > > update_decoder_targets: cxl decoder1.0: dport3 found in target list, index 3 > > > update_decoder_targets: cxl decoder2.0: dport3 found in target list, index 1 > > > update_decoder_targets: cxl decoder2.1: dport3 found in target list, index 1 > > > update_decoder_targets: cxl decoder4.0: dport3 found in target list, index 1 > > > update_decoder_targets: cxl decoder4.1: dport3 found in target list, index 1 > > > > > > Analyzing the conditions when this happens: > > > > > > 1) A dport is shared by multiple decoders. > > > > > > 2) The decoders have interleaving configured (ways > 1). > > > > > > The configuration above has the following hierarchy details (fixed > > > version): > > > > > > root0 > > > |_ > > > | | > > > | decoder0.1 > > > > Hi Robert, > > > > I'm struggling a bit to align this with the above prints. Where is > > decoder1.0 for example? As it's below the root port, I think it's the > > host bridge decoder, which might be this one on your diagram? > > I only showed the detail of the setup that was failing. There is > additional a 4-way config (port1/decoder1.0) and (not visible) some > 1-way configs. Function update_decoder_targets() is not called for > those. > Ah. Ok. Reviewed-by: Jonathan Cameron > Thanks for review, > > -Robert > > > > > Fix makes sense to me. > > > > Jonathan > > > > > > > | ways: 2 > > > | target_list: 0,1 > > > |_______________________________________ > > > | | > > > | dport0 | dport1 > > > | | > > > port2 port4 > > > | | > > > |___________________ |_____________________ > > > | | | | | | > > > | decoder2.0 decoder2.1 | decoder4.0 decoder4.1 > > > | ways: 2 ways: 2 | ways: 2 ways: 2 > > > | target_list: 2,3 target_list: 2,3 | target_list: 2,3 target_list: 2,3 > > > |___________________ |___________________ > > > | | | | > > > | dport2 | dport3 | dport2 | dport3 > > > | | | | > > > endpoint7 endpoint12 endpoint9 endpoint13 > > > |_ |_ |_ |_ > > > | | | | | | | | > > > | decoder7.0 | decoder12.0 | decoder9.0 | decoder13.0 > > > | decoder7.2 | decoder12.2 | decoder9.2 | decoder13.2 > > > | | | | > > > mem3 mem5 mem6 mem8 > > > > > > Note: Device numbers vary for every boot. > > > > > > Current kernel fails to enumerate endpoint12 and endpoint13 as the > > > target list is not updated for the second decoder. > > > > > > Fixes: 4f06d81e7c6a ("cxl: Defer dport allocation for switch ports") > > > Reviewed-by: Dave Jiang > > > Reviewed-by: Alison Schofield > > > Signed-off-by: Robert Richter > > > --- > > > v2: > > > * updated sob-chain, > > > * added fixes tag (Dave). > > > --- > > > drivers/cxl/core/port.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > > > index fef3aa0c6680..3310dbfae9d6 100644 > > > --- a/drivers/cxl/core/port.c > > > +++ b/drivers/cxl/core/port.c > > > @@ -1590,7 +1590,7 @@ static int update_decoder_targets(struct device *dev, void *data) > > > cxlsd->target[i] = dport; > > > dev_dbg(dev, "dport%d found in target list, index %d\n", > > > dport->port_id, i); > > > - return 1; > > > + return 0; > > > } > > > } > > > > > > > > > base-commit: 88c72bab77aaf389beccf762e112828253ca0564 > > > prerequisite-patch-id: f44102a7b095afa1588a5cac012ec2e0d852c021 > > >