Re: [PATCH 3/3] PCI: pciehp: Add dmi table for in-band presence disabled

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On 10/1/19 4:14 PM, Stuart Hayes wrote:
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>
---
  drivers/pci/hotplug/pciehp_hpc.c | 14 ++++++++++++++
  1 file changed, 14 insertions(+)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 1282641c6458..1dd01e752587 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 +27,16 @@
  #include "../pci.h"
  #include "pciehp.h"
+static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
+	{
+		.ident = "Dell System",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc"),
+		},
+	},
+	{}
+};
+

I'm not sure that all Dell systems that were ever made or will be made have in-band presence disabled on all their hotplug slots.

This was a problem with the NVMe hot-swap bays on 14G servers. I can't guarantee that any other slot or machine will need this workaround. The best way I found to implement this is to check for the PCI-ID of the switches behind the port.

Alex



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