Re: [PATCH] PCI/DPC: Extend DPC recovery timeout

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 7/7/25 3:30 AM, Andy Xu wrote:
> From: Hongbo Yao <andy.xu@hj-micro.com>
>
> Extend the DPC recovery timeout from 4 seconds to 7 seconds to
> support Mellanox ConnectX series network adapters.
>
> My environment:
>    - Platform: arm64 N2 based server
>    - Endpoint1: Mellanox Technologies MT27800 Family [ConnectX-5]
>    - Endpoint2: Mellanox Technologies MT2910 Family [ConnectX-7]
>
> With the original 4s timeout, hotplug would still be triggered:
>
> [ 81.012463] pcieport 0004:00:00.0: DPC: containment event, status:0x1f01 source:0x0000
> [ 81.014536] pcieport 0004:00:00.0: DPC: unmasked uncorrectable error detected
> [ 81.029598] pcieport 0004:00:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Receiver ID)
> [ 81.040830] pcieport 0004:00:00.0: device [0823:0110] error status/mask=00008000/04d40000
> [ 81.049870] pcieport 0004:00:00.0: [ 0] ERCR (First)
> [ 81.053520] pcieport 0004:00:00.0: AER: TLP Header: 60008010 010000ff 00001000 9c4c0000
> [ 81.065793] mlx5_core 0004:01:00.0: mlx5_pci_err_detected Device state = 1 health sensors: 1 pci_status: 1. Enter, pci channel state = 2
> [ 81.076183] mlx5_core 0004:01:00.0: mlx5_error_sw_reset:231:(pid 1618): start
> [ 81.083307] mlx5_core 0004:01:00.0: mlx5_error_sw_reset:252:(pid 1618): PCI channel offline, stop waiting for NIC IFC
> [ 81.077428] mlx5_core 0004:01:00.0: E-Switch: Disable: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 81.486693] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid 1618): Skipping wait for vf pages stage
> [ 81.496965] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid 1618): Skipping wait for vf pages stage
> [ 82.395040] mlx5_core 0004:01:00.1: print_health:819:(pid 0): Fatal error detected
> [ 82.395493] mlx5_core 0004:01:00.1: print_health_info:423:(pid 0): PCI slot 1 is unavailable
> [ 83.431094] mlx5_core 0004:01:00.0: mlx5_pci_err_detected Device state = 2 pci_status: 0. Exit, result = 3, need reset
> [ 83.442100] mlx5_core 0004:01:00.1: mlx5_pci_err_detected Device state = 2 health sensors: 1 pci_status: 1. Enter, pci channel state = 2
> [ 83.441801] mlx5_core 0004:01:00.0: mlx5_crdump_collect:50:(pid 2239): crdump: failed to lock gw status -13
> [ 83.454050] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:231:(pid 1618): start
> [ 83.454050] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:252:(pid 1618): PCI channel offline, stop waiting for NIC IFC
> [ 83.849429] mlx5_core 0004:01:00.1: E-Switch: Disable: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 83.858892] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid 1618): Skipping wait for vf pages stage
> [ 83.869464] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid 1618): Skipping wait for vf pages stage
> [ 85.201433] pcieport 0004:00:00.0: pciehp: Slot(41): Link Down
> [ 85.815016] mlx5_core 0004:01:00.1: mlx5_health_try_recover:335:(pid 2239): handling bad device here
> [ 85.824164] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:231:(pid 2239): start
> [ 85.831283] mlx5_core 0004:01:00.1: mlx5_error_sw_reset:252:(pid 2239): PCI channel offline, stop waiting for NIC IFC
> [ 85.841899] mlx5_core 0004:01:00.1: mlx5_unload_one_dev_locked:1612:(pid 2239): mlx5_unload_one_dev_locked: interface is down, NOP
> [ 85.853799] mlx5_core 0004:01:00.1: mlx5_health_wait_pci_up:325:(pid 2239): PCI channel offline, stop waiting for PCI
> [ 85.863494] mlx5_core 0004:01:00.1: mlx5_health_try_recover:338:(pid 2239): health recovery flow aborted, PCI reads still not working
> [ 85.873231] mlx5_core 0004:01:00.1: mlx5_pci_err_detected Device state = 2 pci_status: 0. Exit, result = 3, need reset
> [ 85.879899] mlx5_core 0004:01:00.1: E-Switch: Unload vfs: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 85.921428] mlx5_core 0004:01:00.1: E-Switch: Disable: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 85.930491] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid 1617): Skipping wait for vf pages stage
> [ 85.940849] mlx5_core 0004:01:00.1: mlx5_wait_for_pages:786:(pid 1617): Skipping wait for vf pages stage
> [ 85.949971] mlx5_core 0004:01:00.1: mlx5_uninit_one:1528:(pid 1617): mlx5_uninit_one: interface is down, NOP
> [ 85.959944] mlx5_core 0004:01:00.1: E-Switch: cleanup
> [ 86.035541] mlx5_core 0004:01:00.0: E-Switch: Unload vfs: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 86.077568] mlx5_core 0004:01:00.0: E-Switch: Disable: mode(LEGACY), nvfs(0), neovfs(0), active vports(0)
> [ 86.071727] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid 1617): Skipping wait for vf pages stage
> [ 86.096577] mlx5_core 0004:01:00.0: mlx5_wait_for_pages:786:(pid 1617): Skipping wait for vf pages stage
> [ 86.106909] mlx5_core 0004:01:00.0: mlx5_uninit_one:1528:(pid 1617): mlx5_uninit_one: interface is down, NOP
> [ 86.115940] pcieport 0004:00:00.0: AER: subordinate device reset failed
> [ 86.122557] pcieport 0004:00:00.0: AER: device recovery failed
> [ 86.128571] mlx5_core 0004:01:00.0: E-Switch: cleanup
>
> I added some prints and found that:
>   - ConnectX-5 requires >5s for full recovery
>   - ConnectX-7 requires >6s for full recovery
>
> Setting timeout to 7s covers both devices with safety margin.


Instead of updating the recovery time, can you check why your device recovery takes
such a long time and how to fix it from the device end?


> Signed-off-by: Hongbo Yao <andy.xu@hj-micro.com>
> ---
>   drivers/pci/pcie/dpc.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index fc18349614d7..35a37fd86dcd 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -118,10 +118,10 @@ bool pci_dpc_recovered(struct pci_dev *pdev)
>   	/*
>   	 * Need a timeout in case DPC never completes due to failure of
>   	 * dpc_wait_rp_inactive().  The spec doesn't mandate a time limit,
> -	 * but reports indicate that DPC completes within 4 seconds.
> +	 * but reports indicate that DPC completes within 7 seconds.
>   	 */
>   	wait_event_timeout(dpc_completed_waitqueue, dpc_completed(pdev),
> -			   msecs_to_jiffies(4000));
> +			   msecs_to_jiffies(7000));
>   
>   	return test_and_clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags);
>   }

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer