* [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports
@ 2026-04-02 9:38 Richard Cheng
2026-04-05 7:41 ` Lukas Wunner
2026-04-06 17:35 ` Bjorn Helgaas
0 siblings, 2 replies; 3+ messages in thread
From: Richard Cheng @ 2026-04-02 9:38 UTC (permalink / raw)
To: bhelgaas
Cc: linux-pci, linux-kernel, jan, newtonl, sreddym, skomatineni,
vidyas, kristinc, kaihengf, mochs, Richard Cheng
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports
2026-04-02 9:38 [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports Richard Cheng
@ 2026-04-05 7:41 ` Lukas Wunner
2026-04-06 17:35 ` Bjorn Helgaas
1 sibling, 0 replies; 3+ messages in thread
From: Lukas Wunner @ 2026-04-05 7:41 UTC (permalink / raw)
To: Richard Cheng
Cc: bhelgaas, linux-pci, linux-kernel, jan, newtonl, sreddym,
skomatineni, vidyas, kristinc, kaihengf, mochs
On Thu, Apr 02, 2026 at 05:38:50PM +0800, Richard Cheng wrote:
> 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>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports
2026-04-02 9:38 [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports Richard Cheng
2026-04-05 7:41 ` Lukas Wunner
@ 2026-04-06 17:35 ` Bjorn Helgaas
1 sibling, 0 replies; 3+ messages in thread
From: Bjorn Helgaas @ 2026-04-06 17:35 UTC (permalink / raw)
To: Richard Cheng
Cc: bhelgaas, linux-pci, linux-kernel, jan, newtonl, sreddym,
skomatineni, vidyas, kristinc, kaihengf, mochs
On Thu, Apr 02, 2026 at 05:38:50PM +0800, Richard Cheng wrote:
> 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>
Applied to pci/hotplug for v7.1, thank you!
> ---
> 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-04-02 9:38 [PATCH] PCI/NPEM: Set LED_HW_PLUGGABLE for hotplug-capable ports Richard Cheng
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2026-04-06 17:35 ` Bjorn Helgaas
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