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 disabled.
Signed-off-by: Stuart Hayes <stuart.w.hayes@xxxxxxxxx>
---
v4
add comment to dmi table
drivers/pci/hotplug/pciehp_hpc.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 02d95ab27a12..9541735bd0aa 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -14,6 +14,7 @@
#define dev_fmt(fmt) "pciehp: " fmt
+#include <linux/dmi.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/jiffies.h>
@@ -26,6 +27,24 @@
#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 inline struct pci_dev *ctrl_dev(struct controller *ctrl)
{
return ctrl->pcie->port;
@@ -895,6 +914,9 @@ 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;
+
/*
* If empty slot's power status is on, turn power off. The IRQ isn't
* requested yet, so avoid triggering a notification with this command.
--
2.18.1
