On Tuesday 11 May 2021 22:39:50 Pali Rohár wrote: > Hello! I would like to remind this fix. Is there something else needed > to change? PING > On Wednesday 05 May 2021 18:33:57 Pali Rohár wrote: > > Atheros AR9xxx and QCA9xxx chips have behaviour issues not only after a > > bus reset, but also after doing retrain link, if PCIe bridge is not in > > GEN1 mode (at 2.5 GT/s speed): > > > > - QCA9880 and QCA9890 chips throw a Link Down event and completely > > disappear from the bus and their config space is not accessible > > afterwards. > > > > - QCA9377 chip throws a Link Down event followed by Link Up event, the > > config space is accessible and PCI device ID is correct. But trying to > > access chip's I/O space causes Uncorrected (Non-Fatal) AER error, > > followed by Synchronous external abort 96000210 and Segmentation fault > > of insmod while loading ath10k_pci.ko module. > > > > - AR9390 chip throws a Link Down event followed by Link Up event, config > > space is accessible, but contains nonsense values. PCI device ID is > > 0xABCD which indicates HW bug that chip itself was not able to read > > values from internal EEPROM/OTP. > > > > - AR9287 chip throws also Link Down and Link Up events, also has > > accessible config space containing correct values. But ath9k driver > > fails to initialize card from this state as it is unable to access HW > > registers. This also indicates that the chip iself is not able to read > > values from internal EEPROM/OTP. > > > > These issues related to PCI device ID 0xABCD and to reading internal > > EEPROM/OTP were previously discussed at ath9k-devel mailing list in > > following thread: > > > > https://www.mail-archive.com/ath9k-devel@xxxxxxxxxxxxxxx/msg07529.html > > > > After experiments we've come up with a solution: it seems that Retrain > > link can be called only when using GEN1 PCIe bridge or when PCIe bridge > > link speed is forced to 2.5 GT/s. Applying this workaround fixes all > > mentioned cards. > > > > This issue was reproduced with more cards: > > - Compex WLE900VX (QCA9880 based / device ID 0x003c) > > - QCNFA435 (QCA9377 based / device ID 0x0042) > > - Compex WLE200NX (AR9287 based / device ID 0x002e) > > - "noname" card (QCA9890 based / device ID 0x003c) > > - Wistron NKR-DNXAH1 (AR9390 based / device ID 0x0030) > > on Armada 385 with pci-mvebu.c driver and also on Armada 3720 with > > pci-aardvark.c driver. > > > > To workaround this issue, this change introduces a new PCI quirk called > > PCI_DEV_FLAGS_NO_RETRAIN_LINK_WHEN_NOT_GEN1, which is enabled for all > > Atheros chips with PCI_DEV_FLAGS_NO_BUS_RESET quirk, and also for Atheros > > chip AR9287. > > > > When this quirk is set, kernel disallows triggering PCI_EXP_LNKCTL_RL > > bit in config space of PCIe Bridge in the case when PCIe Bridge is > > capable of higher speed than 2.5 GT/s and this higher speed is already > > allowed. When PCIe Bridge has accessible LNKCTL2 register, we try to > > force target link speed to 2.5 GT/s. After this change it is possible > > to trigger PCI_EXP_LNKCTL_RL bit without issues. > > > > Currently only PCIe ASPM kernel code triggers this PCI_EXP_LNKCTL_RL bit, > > so quirk check is added only into pcie/aspm.c file. > > > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > > Reported-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> > > Tested-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> > > Tested-by: Marek Behún <kabel@xxxxxxxxxx> > > BugLink: https://lore.kernel.org/linux-pci/87h7l8axqp.fsf@xxxxxxx/ > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=84821 > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=192441 > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209833 > > Cc: stable@xxxxxxxxxxxxxxx # c80851f6ce63a ("PCI: Add PCI_EXP_LNKCTL2_TLS* macros") > > > > --- > > Changes since v1: > > * Move whole quirk code into pcie_downgrade_link_to_gen1() function > > * Reformat to 80 chars per line where possible > > * Add quirk also for cards with AR9287 chip (PCI ID 0x002e) > > * Extend commit message description and add information about 0xABCD > > > > Changes since v2: > > * Add quirk also for Atheros QCA9377 chip > > --- > > drivers/pci/pcie/aspm.c | 44 +++++++++++++++++++++++++++++++++++++++++ > > drivers/pci/quirks.c | 39 ++++++++++++++++++++++++++++-------- > > include/linux/pci.h | 2 ++ > > 3 files changed, 77 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > > index ac0557a305af..729b0389562b 100644 > > --- a/drivers/pci/pcie/aspm.c > > +++ b/drivers/pci/pcie/aspm.c > > @@ -192,12 +192,56 @@ static void pcie_clkpm_cap_init(struct pcie_link_state *link, int blacklist) > > link->clkpm_disable = blacklist ? 1 : 0; > > } > > > > +static int pcie_downgrade_link_to_gen1(struct pci_dev *parent) > > +{ > > + u16 reg16; > > + u32 reg32; > > + int ret; > > + > > + /* Check if link is capable of higher speed than 2.5 GT/s */ > > + pcie_capability_read_dword(parent, PCI_EXP_LNKCAP, ®32); > > + if ((reg32 & PCI_EXP_LNKCAP_SLS) <= PCI_EXP_LNKCAP_SLS_2_5GB) > > + return 0; > > + > > + /* Check if link speed can be downgraded to 2.5 GT/s */ > > + pcie_capability_read_dword(parent, PCI_EXP_LNKCAP2, ®32); > > + if (!(reg32 & PCI_EXP_LNKCAP2_SLS_2_5GB)) { > > + pci_err(parent, "ASPM: Bridge does not support changing Link Speed to 2.5 GT/s\n"); > > + return -EOPNOTSUPP; > > + } > > + > > + /* Force link speed to 2.5 GT/s */ > > + ret = pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL2, > > + PCI_EXP_LNKCTL2_TLS, > > + PCI_EXP_LNKCTL2_TLS_2_5GT); > > + if (!ret) { > > + /* Verify that new value was really set */ > > + pcie_capability_read_word(parent, PCI_EXP_LNKCTL2, ®16); > > + if ((reg16 & PCI_EXP_LNKCTL2_TLS) != PCI_EXP_LNKCTL2_TLS_2_5GT) > > + ret = -EINVAL; > > + } > > + > > + if (ret) { > > + pci_err(parent, "ASPM: Changing Target Link Speed to 2.5 GT/s failed: %d\n", ret); > > + return ret; > > + } > > + > > + pci_info(parent, "ASPM: Target Link Speed changed to 2.5 GT/s due to quirk\n"); > > + return 0; > > +} > > + > > static bool pcie_retrain_link(struct pcie_link_state *link) > > { > > struct pci_dev *parent = link->pdev; > > unsigned long end_jiffies; > > u16 reg16; > > > > + if ((link->downstream->dev_flags & PCI_DEV_FLAGS_NO_RETRAIN_LINK_WHEN_NOT_GEN1) && > > + pcie_downgrade_link_to_gen1(parent)) { > > + pci_err(parent, "ASPM: Retrain Link at higher speed is disallowed by quirk\n"); > > + return false; > > + } > > + > > pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16); > > reg16 |= PCI_EXP_LNKCTL_RL; > > pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16); > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > > index 653660e3ba9e..4999ad9d08b8 100644 > > --- a/drivers/pci/quirks.c > > +++ b/drivers/pci/quirks.c > > @@ -3553,23 +3553,46 @@ static void mellanox_check_broken_intx_masking(struct pci_dev *pdev) > > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_MELLANOX, PCI_ANY_ID, > > mellanox_check_broken_intx_masking); > > > > -static void quirk_no_bus_reset(struct pci_dev *dev) > > +static void quirk_no_bus_reset_and_no_retrain_link(struct pci_dev *dev) > > { > > - dev->dev_flags |= PCI_DEV_FLAGS_NO_BUS_RESET; > > + dev->dev_flags |= PCI_DEV_FLAGS_NO_BUS_RESET | > > + PCI_DEV_FLAGS_NO_RETRAIN_LINK_WHEN_NOT_GEN1; > > } > > > > /* > > - * Some Atheros AR9xxx and QCA988x chips do not behave after a bus reset. > > + * Atheros AR9xxx and QCA9xxx chips do not behave after a bus reset and also > > + * after retrain link when PCIe bridge is not in GEN1 mode at 2.5 GT/s speed. > > * The device will throw a Link Down error on AER-capable systems and > > * regardless of AER, config space of the device is never accessible again > > * and typically causes the system to hang or reset when access is attempted. > > + * Or if config space is accessible again then it contains only dummy values > > + * like fixed PCI device ID 0xABCD or values not initialized at all. > > + * Retrain link can be called only when using GEN1 PCIe bridge or when > > + * PCIe bridge has forced link speed to 2.5 GT/s via PCI_EXP_LNKCTL2 register. > > + * To reset these cards it is required to do PCIe Warm Reset via PERST# pin. > > * https://lore.kernel.org/r/20140923210318.498dacbd@xxxxxxxxxxxxxx/ > > + * https://lore.kernel.org/r/87h7l8axqp.fsf@xxxxxxx/ > > + * https://www.mail-archive.com/ath9k-devel@xxxxxxxxxxxxxxx/msg07529.html > > */ > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0030, quirk_no_bus_reset); > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032, quirk_no_bus_reset); > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c, quirk_no_bus_reset); > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033, quirk_no_bus_reset); > > -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034, quirk_no_bus_reset); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x002e, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0030, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c, > > + quirk_no_bus_reset_and_no_retrain_link); > > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0042, > > + quirk_no_bus_reset_and_no_retrain_link); > > + > > +static void quirk_no_bus_reset(struct pci_dev *dev) > > +{ > > + dev->dev_flags |= PCI_DEV_FLAGS_NO_BUS_RESET; > > +} > > > > /* > > * Root port on some Cavium CN8xxx chips do not successfully complete a bus > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > index 86c799c97b77..fdbf7254e4ab 100644 > > --- a/include/linux/pci.h > > +++ b/include/linux/pci.h > > @@ -227,6 +227,8 @@ enum pci_dev_flags { > > PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10), > > /* Don't use Relaxed Ordering for TLPs directed at this device */ > > PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11), > > + /* Don't Retrain Link for device when bridge is not in GEN1 mode */ > > + PCI_DEV_FLAGS_NO_RETRAIN_LINK_WHEN_NOT_GEN1 = (__force pci_dev_flags_t) (1 << 12), > > }; > > > > enum pci_irq_reroute_variant { > > -- > > 2.20.1 > >
