On Tue, Feb 24, 2026 at 12:10:39PM +0100, Mika Westerberg wrote: > Hi all, > > There is (still) an issue with Linux PCIe PTM enabling that happens because > Linux automatically enables PTM if certain capabilities are set. However, > turns out this is not enough because once we enumerate PCIe Switch Upstream > port we also enable PTM but the Downstream Ports are not yet enumerated. > This triggers floods of AER errors like this: > > pcieport 0000:00:07.1: AER: Multiple Uncorrectable (Non-Fatal) error > message received from 0000:00:07.1 > pcieport 0000:00:07.1: PCIe Bus Error: severity=Uncorrectable > (Non-Fatal), type=Transaction Layer, (Receiver ID) > pcieport 0000:00:07.1: device [8086:d44f] error > status/mask=00200000/00000000 > pcieport 0000:00:07.1: [21] ACSViol (First) > pcieport 0000:00:07.1: AER: TLP Header: 0x34000000 0x00000052 > 0x00000000 0x00000000 > pcieport 0000:00:07.1: AER: device recovery successful > pcieport 0000:00:07.1: AER: Uncorrectable (Non-Fatal) error message > received from 0000:00:07.1 > > We have ACS Source Validation enabled so Requester ID 0 which is sent by > the not-enumerated Downstream Port triggers the ACS violation AER. > > This can be prevented by enabling PTM when the whole topology has been > enumerated and doing it like that seems to be reasonable anyway because we > only have a couple of drivers enabling it now so it does not make sense to > enable otherwise as it consumes bandwidth. > > I did that fix and the problem went away but wanted to test with a device > and driver that actually enables PTM. I have a couple of igc NICs here that > has this support. However, when testing I noticed that during power state > transitions we still get errors like this from igc: > > igc 0000:03:00.0 enp3s0: Timeout reading IGC_PTM_STAT register > > and after this PTM for the device stays disabled. > > This series includes fixes for igc that deal with the issues I found and > now PTM gets succesfully enabled and works accross suspend and runtime > suspend of igc, and there are no flood of AER errors as above. While there > there is one cleanup patch in the middle that drops unused parameter. > > Mika Westerberg (5): > igc: Call netif_queue_set_napi() with rntl locked > igc: Let the PCI core deal with the PM resume flow > igc: Don't reset the hardware on suspend path > PCI/PTM: Drop granularity parameter from pci_enable_ptm() > PCI/PTM: Do not enable PTM automatically for Root and Switch Upstream Ports
These last two don't look dependent on the igc patches, so I applied them to pci/ptm for v7.1, thanks! Let me know if there is some dependency and I can ack them and drop them from the PCI tree. > drivers/net/ethernet/intel/ice/ice_main.c | 2 +- > drivers/net/ethernet/intel/idpf/idpf_main.c | 2 +- > drivers/net/ethernet/intel/igc/igc.h | 2 +- > drivers/net/ethernet/intel/igc/igc_ethtool.c | 6 +- > drivers/net/ethernet/intel/igc/igc_main.c | 33 ++++---- > .../net/ethernet/mellanox/mlx5/core/main.c | 2 +- > drivers/pci/pcie/ptm.c | 77 ++++++++++--------- > include/linux/pci.h | 6 +- > 8 files changed, 64 insertions(+), 66 deletions(-) > > -- > 2.50.1 >
