linux-kernel - [PATCH v2 05/12] cxl/acpi: Improve debug messages in cxl_acpi

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Date:   Tue, 18 Oct 2022 15:23:33 +0200
From:   Robert Richter <rrichter@....com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        Robert Richter <rrichter@....com>
Subject: [PATCH v2 05/12] cxl/acpi: Improve debug messages in cxl_acpi_probe()

In cxl_acpi_probe() the iterator bus_for_each_dev() walks through all
CXL hosts. Since all dev_*() debug messages point to the ACPI0017
device which is the CXL root for all hosts, the device information is
pointless as it is always the same device. Change this to use the host
device for this instead.

Also, add additional host specific information such as CXL support,
UID and CHBCR.

This is an example log:

 acpi ACPI0016:00: UID found: 4
 acpi ACPI0016:00: CHBCR found: 0x28090000000
 acpi ACPI0016:00: dport added to root0
 acpi ACPI0016:00: host-bridge: ACPI0016:00
  pci0000:7f: host supports CXL

Signed-off-by: Robert Richter <rrichter@....com>
---
 drivers/cxl/acpi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 31e104f0210f..fb9f72813067 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -221,6 +221,8 @@ static int add_host_bridge_uport(struct device *match, void *arg)
 	if (IS_ERR(port))
 		return PTR_ERR(port);
 
+	dev_info(pci_root->bus->bridge, "host supports CXL\n");
+
 	return 0;
 }
 
@@ -264,11 +266,12 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 	status = acpi_evaluate_integer(bridge->handle, METHOD_NAME__UID, NULL,
 				       &uid);
 	if (status != AE_OK) {
-		dev_err(host, "unable to retrieve _UID of %s\n",
-			dev_name(match));
+		dev_err(match, "unable to retrieve _UID\n");
 		return -ENODEV;
 	}
 
+	dev_dbg(match, "UID found: %lld\n", uid);
+
 	ctx = (struct cxl_chbs_context) {
 		.dev = host,
 		.uid = uid,
@@ -276,11 +279,12 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CHBS, cxl_get_chbcr, &ctx);
 
 	if (ctx.chbcr == 0) {
-		dev_warn(host, "No CHBS found for Host Bridge: %s\n",
-			 dev_name(match));
+		dev_warn(match, "No CHBS found for Host Bridge (UID %lld)\n", uid);
 		return 0;
 	}
 
+	dev_dbg(match, "CHBCR found: 0x%08llx\n", (u64)ctx.chbcr);
+
 	dport = devm_cxl_add_dport(root_port, match, uid, ctx.chbcr);
 	if (IS_ERR(dport))
 		return PTR_ERR(dport);
-- 
2.30.2