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 1A0113FCD for ; Thu, 2 Sep 2021 18:30:33 +0000 (UTC) Received: from fraeml742-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4H0qF91Hynz67jRt; Fri, 3 Sep 2021 02:28:45 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml742-chm.china.huawei.com (10.206.15.223) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Thu, 2 Sep 2021 20:30:30 +0200 Received: from localhost (10.52.127.69) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Thu, 2 Sep 2021 19:30:29 +0100 Date: Thu, 2 Sep 2021 19:30:31 +0100 From: Jonathan Cameron To: Dan Williams CC: , Alison Schofield , , , , , Subject: Re: [PATCH v3 23/28] cxl/acpi: Do not add DSDT disabled ACPI0016 host bridge ports Message-ID: <20210902193031.000035b4@Huawei.com> In-Reply-To: <162982124835.1124374.16212896894542743429.stgit@dwillia2-desk3.amr.corp.intel.com> References: <162982112370.1124374.2020303588105269226.stgit@dwillia2-desk3.amr.corp.intel.com> <162982124835.1124374.16212896894542743429.stgit@dwillia2-desk3.amr.corp.intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; i686-w64-mingw32) Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.52.127.69] X-ClientProxiedBy: lhreml715-chm.china.huawei.com (10.201.108.66) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected On Tue, 24 Aug 2021 09:07:28 -0700 Dan Williams wrote: > From: Alison Schofield > > During CXL ACPI probe, host bridge ports are discovered by scanning > the ACPI0017 root port for ACPI0016 host bridge devices. The scan > matches on the hardware id of "ACPI0016". An issue occurs when an > ACPI0016 device is defined in the DSDT yet disabled on the platform. > Attempts by the cxl_acpi driver to add host bridge ports using a > disabled device fails, and the entire cxl_acpi probe fails. > > The DSDT table includes an _STA method that sets the status and the > ACPI subsystem has checks available to examine it. One such check is > in the acpi_pci_find_root() path. Move the call to acpi_pci_find_root() > to the matching function to prevent this issue when adding either > upstream or downstream ports. You could mention that has the side effect that the existing call in add_host_bridge_uport() is now guarantee not to fail so can be moved closer to where it is used. That chunk had me briefly confused. > > Suggested-by: Dan Williams > Signed-off-by: Alison Schofield > Fixes: 7d4b5ca2e2cb ("cxl/acpi: Add downstream port data to cxl_port instances") > Cc: > Signed-off-by: Dan Williams I'd imagine we want to get this in an early rc so perhaps pull out of this series. Reviewed-by: Jonathan Cameron > --- > drivers/cxl/acpi.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > index 8ae89273f58e..2d8f1ec1abff 100644 > --- a/drivers/cxl/acpi.c > +++ b/drivers/cxl/acpi.c > @@ -243,6 +243,9 @@ static struct acpi_device *to_cxl_host_bridge(struct device *dev) > { > struct acpi_device *adev = to_acpi_device(dev); > > + if (!acpi_pci_find_root(adev->handle)) > + return NULL; > + > if (strcmp(acpi_device_hid(adev), "ACPI0016") == 0) > return adev; > return NULL; > @@ -266,10 +269,6 @@ static int add_host_bridge_uport(struct device *match, void *arg) > if (!bridge) > return 0; > > - pci_root = acpi_pci_find_root(bridge->handle); > - if (!pci_root) > - return -ENXIO; > - > dport = find_dport_by_dev(root_port, match); > if (!dport) { > dev_dbg(host, "host bridge expected and not found\n"); > @@ -282,6 +281,7 @@ static int add_host_bridge_uport(struct device *match, void *arg) > return PTR_ERR(port); > dev_dbg(host, "%s: add: %s\n", dev_name(match), dev_name(&port->dev)); > > + pci_root = acpi_pci_find_root(bridge->handle); > ctx = (struct cxl_walk_context){ > .dev = host, > .root = pci_root->bus, >