[PATCH] pci/hotplug: work-around for missing _RMV on HP ZBook G2

[Jarod Wilson <jarod@redhat.com>]

The HP ZBook 15 and 17 Mobile Workstations, generation 2, up to and
including at least BIOS revision 01.07, do not have an ACPI _RMV object
associated with their expresscard slots, so acpi-based hotplug-capable
slot detection fails. If we fall back to pcie-based detection, the systems
work just fine, so this uses dmi matching to do that. With luck, a future
BIOS will remedy this (I've let someone at HP know about the problem),
but for now, just use this for all existing versions.

Note: they *do* have a proper _RMV object for what I believe is their
thunderbolt ports.

Tested successfully on an HP ZBook 17 G2 and HP ZBook 15 G2.

CC: Len Brown <lenb@kernel.org>
CC: "Rafael J. Wysocki" <rjw@sisk.pl>
CC: Bjorn Helgaas <bhelgaas@google.com>
CC: linux-acpi@vger.kernel.org
CC: linux-pci@vger.kernel.org
Signed-off-by: Jarod Wilson <jarod@redhat.com>
---
 drivers/pci/hotplug/pciehp_acpi.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/pci/hotplug/pciehp_acpi.c b/drivers/pci/hotplug/pciehp_acpi.c
index 93cc926..db38fb5 100644
--- a/drivers/pci/hotplug/pciehp_acpi.c
+++ b/drivers/pci/hotplug/pciehp_acpi.c
@@ -28,6 +28,7 @@
 #include <linux/pci_hotplug.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/dmi.h>
 #include "pciehp.h"
 
 #define PCIEHP_DETECT_PCIE	(0)
@@ -109,10 +110,40 @@ static struct pcie_port_service_driver __initdata dummy_driver = {
 	.probe		= dummy_probe,
 };
 
+static int __init set_slot_detection_mode_pcie(const struct dmi_system_id *d)
+{
+	info("%s lacks ACPI _RMV object for expresscard\n", d->ident);
+	return 1;
+}
+
+static struct dmi_system_id __initdata missing_acpi_rmv[] = {
+	/* ZBook 17 through at least bios v01.07 */
+	{
+	 .callback = set_slot_detection_mode_pcie,
+	 .ident = "HP ZBook 17 G2 Mobile Workstation",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 17 G2"),
+		},
+	},
+	/* ZBook 15 through at least bios v01.07 */
+	{
+	 .callback = set_slot_detection_mode_pcie,
+	 .ident = "HP ZBook 15 G2 Mobile Workstation",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 15 G2"),
+		},
+	},
+	{ .ident = NULL }
+};
+
 static int __init select_detection_mode(void)
 {
 	struct dummy_slot *slot, *tmp;
 
+	if (dmi_check_system(missing_acpi_rmv))
+		return PCIEHP_DETECT_PCIE;
 	if (pcie_port_service_register(&dummy_driver))
 		return PCIEHP_DETECT_ACPI;
 	pcie_port_service_unregister(&dummy_driver);
@@ -134,4 +165,6 @@ void __init pciehp_acpi_slot_detection_init(void)
 out:
 	if (slot_detection_mode == PCIEHP_DETECT_ACPI)
 		info("Using ACPI for slot detection.\n");
+	else if (slot_detection_mode == PCIEHP_DETECT_PCIE)
+		info("Using PCIE-based slot detection.\n");
 }
-- 
1.8.3.1