[PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports

[Richard Cheng <icheng@nvidia.com>]

NPEM registers LED classdevs on PCI endpoint that may be behind
hotplug-capable ports. During hot-removal, led_classdev_unregister()
calls led_set_brightness(LED_OFF) which PCI config on a disconnected
device, returning -ENODEV:

```
leds 0003:01:00.0:enclosure:ok: Setting an LED's brightness failed (-19)
```

The LED core already suppresses this for devices with LED_HW_PLUGGABLE
set, but NPEM never sets it. Add the flag since NPEM LEDs are on
hot-pluggable hardware by nature.

Fixes: 4e893545ef87 ("PCI/NPEM: Add Native PCIe Enclosure Management support")
Signed-off-by: Richard Cheng <icheng@nvidia.com>
Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
---
The bug was triggered on an ARM64 machine with CPU model Olympus.
Kernel version is v6.17.
The PCI topology is
```
$ sudo lspci -tv
-[0001:00]---00.0-[01]--+-00.0  Mellanox Technologies CX8 Family [ConnectX-8]
                        +-00.1  Mellanox Technologies CX8 Family [ConnectX-8]
                        +-00.2  Mellanox Technologies CX8 Family [ConnectX-8]
                        \-00.3  Mellanox Technologies CX8 Family [ConnectX-8]
-[0002:00]---00.0-[01]--
-+-[0003:00]---00.0-[01]----00.0  Montage Technology Co., Ltd. Device c002
 \-[0003:80]---00.0-[81]----00.0  Montage Technology Co., Ltd. Device c002
-[0004:00]---00.0-[01]--
-+-[0005:00]---00.0-[01]----00.0  Samsung Electronics Co Ltd Device a810
 +-[0005:40]---00.0-[41]----00.0  Samsung Electronics Co Ltd Device a810
 +-[0005:c0]---00.0-[c1]----00.0  Intel Corporation I210 Gigabit Network Connection
 \-[0005:e0]---00.0-[e1-e2]----00.0-[e2]--+-00.0  ASPEED Technology, Inc. ASPEED Graphics Family
                                          \-02.0  ASPEED Technology, Inc. Device 2603
-+-[0006:00]---00.0-[01]--
 \-[0006:80]---00.0-[81]--
```
We're targeting on 0003:01:00.0 CXL [0502]: Montage Technology Co., Ltd. Device [1b00:c002] (rev 03).
First use `sudo setpci -s 0003:00:00.0 0x1f4.w=0x0002` to set UnmaskLinkDisable in CXL DVSEC.
Then disable the link with `sudo setpci -v -s 0003:00:00.0 CAP_EXP+0x10.b=0x10:0x10`


Best regards,
Richard Cheng.
---
 drivers/pci/npem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/npem.c b/drivers/pci/npem.c
index ffeeedf6e311..c51879fcd438 100644
--- a/drivers/pci/npem.c
+++ b/drivers/pci/npem.c
@@ -504,7 +504,7 @@ static int pci_npem_set_led_classdev(struct npem *npem, struct npem_led *nled)
 	led->brightness_get = brightness_get;
 	led->max_brightness = 1;
 	led->default_trigger = "none";
-	led->flags = 0;
+	led->flags = LED_HW_PLUGGABLE;
 
 	ret = led_classdev_register(&npem->dev->dev, led);
 	if (ret)
-- 
2.43.0