| Message ID | 20250404041810.245984-3-sanastasio@raptorengineering.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | PowerNV PCIe Hotplug Driver Fixes | expand |
[cc += Krishna] On Thu, Apr 03, 2025 at 11:18:09PM -0500, Shawn Anastasio wrote: > The Microsemi Switchtec PM8533 PFX 48xG3 [11f8:8533] PCIe switch system > was observed to incorrectly assert the Presence Detect Set bit in its > capabilities when tested on a Raptor Computing Systems Blackbird system, > resulting in the hot insert path never attempting a rescan of the bus > and any downstream devices not being re-detected. > > Work around this by additionally checking whether the PCIe data link is > active or not when performing presence detection on downstream switches' > ports, similar to the pciehp_hpc.c driver. [...] > --- a/drivers/pci/hotplug/pnv_php.c > +++ b/drivers/pci/hotplug/pnv_php.c > @@ -390,6 +390,20 @@ static int pnv_php_get_power_state(struct hotplug_slot *slot, u8 *state) > return 0; > } > > +static int pcie_check_link_active(struct pci_dev *pdev) > +{ > + u16 lnk_status; > + int ret; > + > + ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); > + if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status)) > + return -ENODEV; > + > + ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); > + > + return ret; > +} > + This appears to be a 1:1 copy of pciehp_check_link_active(), save for the ctrl_dbg() call. For the sake of code-reuse, please move the function into the PCI library drivers/pci/pci.c so that it can be used everywhere. Note that there's another patch pending which does exactly that: https://lore.kernel.org/r/20250225-qps615_v4_1-v4-7-e08633a7bdf8@oss.qualcomm.com/ So either include that patch in your series (addressing the review feedback I sent for it and cc'ing the original submitter) or wait for it to be respun by the original submitter. Thanks, Lukas
diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c index 2c07544216fb..1a734adb5b10 100644 --- a/drivers/pci/hotplug/pnv_php.c +++ b/drivers/pci/hotplug/pnv_php.c @@ -390,6 +390,20 @@ static int pnv_php_get_power_state(struct hotplug_slot *slot, u8 *state) return 0; } +static int pcie_check_link_active(struct pci_dev *pdev) +{ + u16 lnk_status; + int ret; + + ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status); + if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status)) + return -ENODEV; + + ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA); + + return ret; +} + static int pnv_php_get_adapter_state(struct hotplug_slot *slot, u8 *state) { struct pnv_php_slot *php_slot = to_pnv_php_slot(slot); @@ -402,6 +416,19 @@ static int pnv_php_get_adapter_state(struct hotplug_slot *slot, u8 *state) */ ret = pnv_pci_get_presence_state(php_slot->id, &presence); if (ret >= 0) { + if (pci_pcie_type(php_slot->pdev) == PCI_EXP_TYPE_DOWNSTREAM && + presence == OPAL_PCI_SLOT_EMPTY) { + /* + * Similar to pciehp_hpc, check whether the Link Active + * bit is set to account for broken downstream bridges + * that don't properly assert Presence Detect State, as + * was observed on the Microsemi Switchtec PM8533 PFX + * [11f8:8533]. + */ + if (pcie_check_link_active(php_slot->pdev) > 0) + presence = OPAL_PCI_SLOT_PRESENT; + } + *state = presence; ret = 0; } else {
The Microsemi Switchtec PM8533 PFX 48xG3 [11f8:8533] PCIe switch system was observed to incorrectly assert the Presence Detect Set bit in its capabilities when tested on a Raptor Computing Systems Blackbird system, resulting in the hot insert path never attempting a rescan of the bus and any downstream devices not being re-detected. Work around this by additionally checking whether the PCIe data link is active or not when performing presence detection on downstream switches' ports, similar to the pciehp_hpc.c driver. Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com> --- drivers/pci/hotplug/pnv_php.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)