On Tue, Jul 15, 2025 at 07:51:04PM +0530, Manivannan Sadhasivam via B4 Relay
wrote:
> From: Manivannan Sadhasivam <m...@kernel.org>
>
> Some host bridge devices require resetting the Root Ports in a platform
> specific way to recover them from error conditions such as Fatal AER
> errors, Link Down etc... So introduce pci_host_bridge::reset_root_port()
> callback and call it from pcibios_reset_secondary_bus() if available. Also,
> save the Root Port config space before reset and restore it afterwards.
>
> The 'reset_root_port' callback is responsible for resetting the given Root
> Port referenced by the 'pci_dev' pointer in a platform specific way and
> bring it back to the working state if possible. If any error occurs during
> the reset operation, relevant errno should be returned.
Reviewed-by: Frank Li <frank...@nxp.com>
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasi...@linaro.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasi...@oss.qualcomm.com>
> ---
> drivers/pci/pci.c | 20 ++++++++++++++++++++
> drivers/pci/pcie/err.c | 5 -----
> include/linux/pci.h | 1 +
> 3 files changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index
> e9448d55113bdfd2263d8e2f6b3ec802f56b712e..b29264aa2be33b18a58b3b3db1d1fb0f6483e5e8
> 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4964,6 +4964,26 @@ void pci_reset_secondary_bus(struct pci_dev *dev)
>
> void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
> {
> + struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> + int ret;
> +
> + if (pci_is_root_bus(dev->bus) && host->reset_root_port) {
> + /*
> + * Save the config space of the Root Port before doing the
> + * reset, since the state could be lost. The Endpoint state
> + * should've been saved by the caller.
> + */
> + pci_save_state(dev);
> + ret = host->reset_root_port(host, dev);
> + if (ret)
> + pci_err(dev, "Failed to reset Root Port: %d\n", ret);
> + else
> + /* Now restore it on success */
> + pci_restore_state(dev);
> +
> + return;
> + }
> +
> pci_reset_secondary_bus(dev);
> }
>
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index
> de6381c690f5c21f00021cdc7bde8d93a5c7db52..b834fc0d705938540d3d7d3d8739770c09fe7cf1
> 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -234,11 +234,6 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> }
>
> if (status == PCI_ERS_RESULT_NEED_RESET) {
> - /*
> - * TODO: Should call platform-specific
> - * functions to reset slot before calling
> - * drivers' slot_reset callbacks?
> - */
> status = PCI_ERS_RESULT_RECOVERED;
> pci_dbg(bridge, "broadcast slot_reset message\n");
> pci_walk_bridge(bridge, report_slot_reset, &status);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index
> 05e68f35f39238f8b9ce08df97b384d1c1e89bbe..e7c118a961910a307ec365f17b8fe4f2585267e8
> 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -599,6 +599,7 @@ struct pci_host_bridge {
> void (*release_fn)(struct pci_host_bridge *);
> int (*enable_device)(struct pci_host_bridge *bridge, struct pci_dev
> *dev);
> void (*disable_device)(struct pci_host_bridge *bridge, struct pci_dev
> *dev);
> + int (*reset_root_port)(struct pci_host_bridge *bridge, struct pci_dev
> *dev);
> void *release_data;
> unsigned int ignore_reset_delay:1; /* For entire hierarchy */
> unsigned int no_ext_tags:1; /* No Extended Tags */
>
> --
> 2.45.2
>
>
