PCI: pciehp: Add DMI table for in-band presence detection disabled

mainline inclusion
from mainline-v5.7-rc1
commit 0b382546
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V
CVE: NA

--------------------------------

Some systems have in-band presence detection disabled for hot-plug PCI
slots but do not report this in the slot capabilities 2 (SLTCAP2) register.
On these systems, presence detect can become active well after the link is
reported to be active, which can cause the slots to be disabled after a
device is connected.

Add a DMI table to flag these systems as having in-band presence detect
disabled.

Link: https://lore.kernel.org/r/20191025190047.38130-4-stuart.w.hayes@gmail.comSigned-off-by: NStuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/pci/hotplug/pciehp_hpc.c

@@ -12,6 +12,7 @@
  * Send feedback to <greg@kroah.com>,<kristen.c.accardi@intel.com>
  */
 
+#include <linux/dmi.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/types.h>
@@ -27,6 +28,24 @@
 #include "../pci.h"
 #include "pciehp.h"
 
+static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
+	/*
+	 * Match all Dell systems, as some Dell systems have inband
+	 * presence disabled on NVMe slots (but don't support the bit to
+	 * report it). Setting inband presence disabled should have no
+	 * negative effect, except on broken hotplug slots that never
+	 * assert presence detect--and those will still work, they will
+	 * just have a bit of extra delay before being probed.
+	 */
+	{
+		.ident = "Dell System",
+		.matches = {
+			DMI_MATCH(DMI_OEM_STRING, "Dell System"),
+		},
+	},
+	{}
+};
+
 static irqreturn_t pciehp_isr(int irq, void *dev_id);
 static irqreturn_t pciehp_ist(int irq, void *dev_id);
 static int pciehp_poll(void *data);
@@ -980,6 +999,9 @@ struct controller *pcie_init(struct pcie_device *dev)
 		ctrl->inband_presence_disabled = 1;
 	}
 
+	if (dmi_first_match(inband_presence_disabled_dmi_table))
+		ctrl->inband_presence_disabled = 1;
+
 	/* Check if Data Link Layer Link Active Reporting is implemented */
 	pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, &link_cap);