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Message-ID: <20250619093228.283171-1-andy.xu@hj-micro.com>
Date: Thu, 19 Jun 2025 17:32:28 +0800
From: Hongbo Yao <andy.xu@...micro.com>
To: bhelgaas@...gle.com,
lukas@...ner.de
Cc: linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
peter.du@...micro.com,
jemma.zhang@...micro.com,
Hongbo Yao <andy.xu@...micro.com>
Subject: [RFC PATCH] PCI: pciehp: Replace fixed delay with polling for slot power-off
Fixed 1-second delay in remove_board() fails to accommodate certain
hardware like multi-host OCP cards, which exhibit longer power-off
latencies.
Failure scenario:
1. Software clears pending_events prematurely
2. Hardware triggers DLLSC after software clearance
3. Subsequent power-off process may generate AER interrupts
4. System misinterprets residual DLLSC as valid hotplug event
Fix this by replacing the fixed delay with polling for DLLLA bit in
the link status register.
Logs before fix:
[157.778307] pcieport 0003:00:00.0: pciehp: pending interrupts 0x0001 from Slot Status
[157.778321] pcieport 0003:00:00.0: pciehp: Slot(31): Attention button pressed
[157.785445] pcieport 0003:00:00.0: pciehp: Slot(31): Powering off due to button press
[157.798931] pcieport 000b:00:02.0: pciehp: pending interrupts 0x0001 from Slot Status
[157.799263] pcieport 0003:00:00.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 2c0
[157.799273] pcieport 000b:00:02.0: pciehp: Slot(113): Attention button pressed
[157.800484] pcieport 000b:00:02.0: pciehp: Slot(113): Powering off due to button press
[157.800830] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 2c0
[162.850249] pcieport 0003:00:00.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 12e1
[162.850251] pcieport 000b:00:02.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 12e1
[162.850253] pcieport 0003:00:00.0: pciehp: pciehp_unconfigure_device: domain:bus:dev = 0003:01:00
[162.850254] pcieport 000b:00:02.0: pciehp: pciehp_unconfigure_device: domain:bus:dev = 000b:02:00
[162.850278] mlx5_core 000b:02:00.1: PME# disabled
[164.862362] mlx5_core 000b:02:00.1: E-Switch: cleanup
[165.171541] mlx5_core 000b:02:00.1: disabling bus mastering
[165.171591] mlx5_core 000b:02:00.0: PME# disabled
[167.214351] mlx5_core 000b:02:00.0: E-Switch: cleanup
[167.539871] mlx5_core 000b:02:00.0: disabling bus mastering
[167.540342] pcieport 000b:00:02.0: pciehp: pciehp_power_off_slot: SLOTCTRL 88 write cmd 400
[167.540345] mlx5_core 0003:01:00.1: PME# disabled
[168.546269] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 300
[169.590320] mlx5_core 0003:01:00.1: E-Switch: cleanup
[169.899852] mlx5_core 0003:01:00.1: disabling bus mastering
[169.899241] mlx5_core 0003:01:00.0: PME# disabled
[171.870344] mlx5_core 0003:01:00.0: E-Switch: cleanup
[172.289046] mlx5_core 0003:01:00.0: disabling bus mastering
[172.289366] pcieport 0003:00:00.0: pciehp: pciehp_power_off_slot: SLOTCTRL 88 write cmd 400
[172.302385] pcieport 0003:00:00.0: AER: Corrected error message received from 0003:00:00.0
[172.302396] pcieport 000b:00:02.0: AER: Corrected error message received from 000b:00:02.0
[172.310641] pcieport 0003:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[172.310892] pcieport 000b:00:02.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[172.310893] pcieport 0003:00:00.0: device [0823:0110] error status/mask=00000001/0000e000
[172.310894] pcieport 0003:00:00.0: [ 0] RxErr
[172.310893] pcieport 000b:00:02.0: device [0823:0112] error status/mask=00000001/0000e000
[172.310894] pcieport 000b:00:02.0: [ 0] RxErr (First)
[172.332915] pcieport 0003:00:00.0: pciehp: pending interrupts 0x0100 from Slot Status
[172.353876] pcieport 000b:00:02.0: pciehp: pending interrupts 0x0100 from Slot Status
[172.360212] pcieport 000b:00:02.0: pciehp: pciehp_check_link_active: lnk_status = d011
[172.360362] pcieport 000b:00:02.0: pciehp: Slot(113): Card present
[172.374314] pcieport 000b:00:02.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 17e1
[172.374357] pcieport 000b:00:02.0: pciehp: pciehp_power_on_slot: SLOTCTRL 88 write cmd 0
[172.374383] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 200
[173.314226] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 300
[174.111245] pcieport 0003:00:00.0: pciehp: pending interrupts 0x0100 from Slot Status
[174.111232] pcieport 0003:00:00.0: pciehp: pciehp_check_link_active: lnk_status = f085
[174.111234] pcieport 0003:00:00.0: pciehp: Slot(31): Card present
[174.117136] pcieport 0003:00:00.0: pciehp: Slot(31): Link Up
[174.122963] pcieport 0003:00:00.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 17e1
[174.122964] pcieport 0003:00:00.0: pciehp: pciehp_power_on_slot: SLOTCTRL 88 write cmd 0
[174.122967] pcieport 0003:00:00.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 200
Logs after fix:
[143.610100] pcieport 000b:00:02.0: pciehp: pending interrupts 0x0001 from Slot Status
[143.616525] pcieport 0003:00:00.0: pciehp: pending interrupts 0x0001 from Slot Status
[143.629921] pcieport 000b:00:02.0: pciehp: Slot(113): Attention button pressed
[143.629923] pcieport 000b:00:02.0: pciehp: Slot(113): Powering off due to button press
[143.629926] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 2c0
[143.651725] pcieport 0003:00:00.0: pciehp: Slot(31): Attention button pressed
[143.658848] pcieport 0003:00:00.0: pciehp: Slot(31): Powering off due to button press
[143.666666] pcieport 0003:00:00.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 2c0
[148.863526] pcieport 000b:00:02.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 12e1
[148.870562] pcieport 0003:00:00.0: pciehp: pciehp_get_power_status: SLOTCTRL 88 value read 12e1
[148.870572] pcieport 0003:00:00.0: pciehp: pciehp_unconfigure_device: domain:bus:dev = 0003:01:00
[148.870579] pcieport 000b:00:02.0: pciehp: pciehp_unconfigure_device: domain:bus:dev = 000b:02:00
[148.870605] mlx5_core 0003:01:00.1: PME# disabled
[152.536968] mlx5_core 0003:01:00.1: E-Switch: cleanup
[152.877666] mlx5_core 0003:01:00.1: disabling bus mastering
[152.878202] mlx5_core 0003:01:00.0: PME# disabled
[156.592567] mlx5_core 0003:01:00.0: E-Switch: cleanup
[156.904767] mlx5_core 0003:01:00.0: disabling bus mastering
[156.905195] pcieport 0003:00:00.0: pciehp: pciehp_power_off_slot: SLOTCTRL 88 write cmd 400
[156.905231] mlx5_core 000b:02:00.1: PME# disabled
[160.360660] mlx5_core 000b:02:00.1: E-Switch: cleanup
[161.272871] mlx5_core 000b:02:00.1: disabling bus mastering
[161.273719] mlx5_core 000b:02:00.0: PME# disabled
[165.028632] mlx5_core 000b:02:00.0: E-Switch: cleanup
[165.454213] mlx5_core 000b:02:00.0: disabling bus mastering
[165.454925] pcieport 000b:00:02.0: pciehp: pciehp_power_off_slot: SLOTCTRL 88 write cmd 400
[165.464333] pcieport 0003:00:00.0: AER: Corrected error message received from 0003:00:00.0
[165.478716] pcieport 000b:00:02.0: AER: Corrected error message received from 000b:00:02.0
[165.481156] pcieport 0003:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[165.481158] pcieport 0003:00:00.0: device [0823:0110] error status/mask=00000001/0000e000
[165.481166] pcieport 0003:00:00.0: [ 0] RxErr (First)
[165.528873] pcieport 000b:00:02.0: pciehp: pending interrupts 0x0001 from Slot Status
[165.535384] pcieport 0003:00:00.0: pciehp: pending interrupts 0x0100 from Slot Status
[165.535403] pcieport 000b:00:02.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
[165.535403] pcieport 000b:00:02.0: device [0823:0112] error status/mask=00000001/0000e000
[165.541315] pcieport 0003:00:00.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 300
[165.550871] pcieport 0003:00:00.0: [ 0] RxErr (First)
[165.578591] pcieport 000b:00:02.0: pciehp: pciehp_set_indicators: SLOTCTRL 88 write cmd 300
Signed-off-by: Hongbo Yao <andy.xu@...micro.com>
---
drivers/pci/hotplug/pciehp_ctrl.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index bcc938d4420f..179ebe4f7797 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -30,6 +30,25 @@
#define SAFE_REMOVAL true
#define SURPRISE_REMOVAL false
+static void pciehp_wait_for_link_inactive(struct controller *ctrl)
+{
+ u16 lnk_status;
+ int timeout = 10000, step = 20;
+
+ do {
+ pcie_capability_read_word(ctrl->pcie->port, PCI_EXP_LNKSTA,
+ &lnk_status);
+
+ if (!(lnk_status & PCI_EXP_LNKSTA_DLLLA))
+ return;
+
+ msleep(step);
+ timeout -= step;
+ } while (timeout >= 0);
+
+ ctrl_dbg(ctrl, "Timeout waiting for link inactive state\n");
+}
+
static void set_slot_off(struct controller *ctrl)
{
/*
@@ -119,8 +138,11 @@ static void remove_board(struct controller *ctrl, bool safe_removal)
* After turning power off, we must wait for at least 1 second
* before taking any action that relies on power having been
* removed from the slot/adapter.
+ *
+ * Extended wait with polling to ensure hardware has completed
+ * power-off sequence.
*/
- msleep(1000);
+ pciehp_wait_for_link_inactive(ctrl);
/* Ignore link or presence changes caused by power off */
atomic_and(~(PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC),
--
2.43.0
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