Hi, Currently, in the event of AER/DPC, PCI core will try to reset the slot (Root Port) and its subordinate devices by invoking bridge control reset and FLR. But in some cases like AER Fatal error, it might be necessary to reset the Root Ports using the PCI host bridge drivers in a platform specific way (as indicated by the TODO in the pcie_do_recovery() function in drivers/pci/pcie/err.c). Otherwise, the PCI link won't be recovered successfully.
So this series adds a new callback 'pci_host_bridge::reset_root_port' for the host bridge drivers to reset the Root Port when a fatal error happens. Also, this series allows the host bridge drivers to handle PCI link down event by resetting the Root Ports and recovering the bus. This is accomplished by the help of the new 'pci_host_handle_link_down()' API. Host bridge drivers are expected to call this API (preferrably from a threaded IRQ handler) with relevant Root Port 'pci_dev' when a link down event is detected for the port. The API will reuse the pcie_do_recovery() function to recover the link if AER support is enabled, otherwise it will directly call the reset_root_port() callback of the host bridge driver (if exists). For reference, I've modified the pcie-qcom driver to call pci_host_handle_link_down() API with Root Port 'pci_dev' after receiving the LINK_DOWN global_irq event and populated 'pci_host_bridge::reset_root_port()' callback to reset the Root Port. Since the Qcom PCIe controllers support only a single Root Port (slot) per controller instance, the API is going to be invoked only once. For multi Root Port controllers, the controller driver is expected to detect the Root Port that received the link down event and call the pci_host_handle_link_down() API with 'pci_dev' of that Root Port. Testing ------- I've lost access to my test setup now. So Krishna (Cced) will help with testing on the Qcom platform and Wilfred or Niklas should be able to test it on Rockchip platform. For the moment, this series is compile tested only. Changes in v6: - Incorporated the patch: https://lore.kernel.org/all/20250524185304.26698-2-manivannan.sadhasi...@linaro.org/ - Link to v5: https://lore.kernel.org/r/20250715-pci-port-reset-v5-0-26a5d278d...@oss.qualcomm.com Changes in v5: * Reworked the pci_host_handle_link_down() to accept Root Port instead of resetting all Root Ports in the event of link down. * Renamed 'reset_slot' to 'reset_root_port' to avoid confusion as both terms were used interchangibly and the series is intended to reset Root Port only. * Added the Rockchip driver change to this series. * Dropped the applied patches and review/tested tags due to rework. * Rebased on top of v6.16-rc1. Changes in v4: - Handled link down first in the irq handler - Updated ICC & OPP bandwidth after link up in reset_slot() callback - Link to v3: https://lore.kernel.org/r/20250417-pcie-reset-slot-v3-0-59a10811c...@linaro.org Changes in v3: - Made the pci-host-common driver as a common library for host controller drivers - Moved the reset slot code to pci-host-common library - Link to v2: https://lore.kernel.org/r/20250416-pcie-reset-slot-v2-0-efe76b278...@linaro.org Changes in v2: - Moved calling reset_slot() callback from pcie_do_recovery() to pcibios_reset_secondary_bus() - Link to v1: https://lore.kernel.org/r/20250404-pcie-reset-slot-v1-0-98952918b...@linaro.org Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasi...@oss.qualcomm.com> --- Manivannan Sadhasivam (3): PCI/ERR: Add support for resetting the Root Ports in a platform specific way PCI: host-common: Add link down handling for Root Ports PCI: qcom: Add support for resetting the Root Port due to link down event Wilfred Mallawa (1): PCI: dw-rockchip: Add support to reset Root Port upon link down event drivers/pci/controller/dwc/Kconfig | 2 + drivers/pci/controller/dwc/pcie-dw-rockchip.c | 91 ++++++++++++++++++- drivers/pci/controller/dwc/pcie-qcom.c | 120 ++++++++++++++++++++++++-- drivers/pci/controller/pci-host-common.c | 33 +++++++ drivers/pci/controller/pci-host-common.h | 1 + drivers/pci/pci.c | 21 +++++ drivers/pci/pcie/err.c | 6 +- include/linux/pci.h | 1 + 8 files changed, 260 insertions(+), 15 deletions(-) --- base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 change-id: 20250715-pci-port-reset-4d9519570123 Best regards, -- Manivannan Sadhasivam <manivannan.sadhasi...@oss.qualcomm.com>
