Re: [PATCH 2/4] PCI/ERR: Add support for resetting the slot in a platforms specific way

[Lukas Wunner <lukas@wunner.de>]

On Fri, Apr 04, 2025 at 01:52:22PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> When the PCI error handling requires resetting the slot, reset it using the
> host bridge specific 'reset_slot' callback if available before calling the
> 'slot_reset' callback of the PCI drivers.
> 
> The 'reset_slot' callback is responsible for resetting the given slot
> 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 slot
> reset operation, relevant errno should be returned.
[...]
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -234,11 +234,16 @@ 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?
> -		 */
> +		if (host->reset_slot) {
> +			ret = host->reset_slot(host, bridge);
> +			if (ret) {
> +				pci_err(bridge, "failed to reset slot: %d\n",
> +					ret);
> +				status = PCI_ERS_RESULT_DISCONNECT;
> +				goto failed;
> +			}
> +		}
> +

This feels like something that should be plumbed into
pcibios_reset_secondary_bus(), rather than pcie_do_recovery().

Note that in the DPC case, pcie_do_recovery() doesn't issue a reset
itself.  The reset has already happened, it was automatically done
by the hardware and all the kernel needs to do is bring up the link
again.  Do you really need any special handling for that in the
host controller driver?

Only in the AER case do you want to issue a reset on the secondary bus
and if there's any platform-specific support needed for that, it needs
to go into pcibios_reset_secondary_bus().

Thanks,

Lukas