Hotplug ports need to be in D0 to access devices on their secondary bus.
pciehp itself does this in
pciehp_check_link_status(),
pciehp_configure_device() (both called from board_added())
and
pciehp_unconfigure_device() (called from remove_board()).
In addition, Yinghai Lu discovered that some Skylake server CPUs or PCHs
feature a Power Controller for their PCIe hotplug ports (PCIe r3.1, sec
6.7.1.8) which requires the port to be in D0 when invoking
pciehp_power_on_slot() (likewise called from board_added()).
The spec is silent about such a requirement, but it seems prudent to
assume that any hotplug port with a Power Controller may need this.
Thus, acquire a runtime PM ref for the invocation of board_added() and
remove_board().
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Cc: Erik Veijola <erik.veijola@xxxxxxxxxxxxxxx>
Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Krishna Dhulipala <krishnad@xxxxxx>
Cc: Wei Zhang <wzhang@xxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/pci/hotplug/pciehp_ctrl.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index ec0b4c11ccd9..d071aa63dac9 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -31,6 +31,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
+#include <linux/pm_runtime.h>
#include <linux/pci.h>
#include "../pci.h"
#include "pciehp.h"
@@ -390,6 +391,7 @@ int pciehp_enable_slot(struct slot *p_slot)
{
u8 getstatus = 0;
struct controller *ctrl = p_slot->ctrl;
+ int retval;
pciehp_get_adapter_status(p_slot, &getstatus);
if (!getstatus) {
@@ -414,7 +416,10 @@ int pciehp_enable_slot(struct slot *p_slot)
}
}
- return board_added(p_slot);
+ pm_runtime_get_sync(&ctrl->pcie->port->dev);
+ retval = board_added(p_slot);
+ pm_runtime_put(&ctrl->pcie->port->dev);
+ return retval;
}
/*
@@ -424,6 +429,7 @@ int pciehp_disable_slot(struct slot *p_slot)
{
u8 getstatus = 0;
struct controller *ctrl = p_slot->ctrl;
+ int retval;
if (!p_slot->ctrl)
return 1;
@@ -437,7 +443,10 @@ int pciehp_disable_slot(struct slot *p_slot)
}
}
- return remove_board(p_slot);
+ pm_runtime_get_sync(&ctrl->pcie->port->dev);
+ retval = remove_board(p_slot);
+ pm_runtime_put(&ctrl->pcie->port->dev);
+ return retval;
}
int pciehp_sysfs_enable_slot(struct slot *p_slot)
--
2.11.0
