答复: [外部邮件] Re: [PATCH] PCI: Save the Root Port state before a platform-specific reset

["Li,Rongqing" <lirongqing@baidu.com>]

> 
> [Severity: High]
> Does calling pci_save_state(dev) here overwrite the Root Port's working saved
> state (saved during enumeration in pci_bus_add_device() and
> pcie_portdrv_probe()) with post-error or post-link-down register values?
> 
> During link-down recovery via pci_host_handle_link_down() ->
> pcie_do_recovery() -> pci_host_reset_root_port() -> pci_bus_error_reset(), the
> link is already down before pcibios_reset_secondary_bus() runs.  Downstream
> Ports clear PCI_EXP_DEVCTL2_LTR_EN on link down (and
> pci_bridge_reconfigure_ltr() in pci_restore_pcie_state() is a no-op for Root Ports
> because
> pci_upstream_bridge(dev) is NULL), while controllers such as pcie-dw-rockchip
> and pcie-qcom have already reset their non-sticky Root Port registers on the
> link-down event.  Saving state at this point captures those cleared registers and
> restores them after host->reset_root_port().
> 
> Similarly, in the fatal AER recovery path, aer_root_reset() disables Root Port AER
> interrupts before resetting the bus:
> 
> drivers/pci/pcie/aer.c:aer_root_reset() {
> 	if (host->native_aer && aer)
> 		aer_disable_irq(root);
> 	...
> 	} else {
> 		rc = pci_bus_error_reset(dev);
> }
> 
> Calling pci_save_state(dev) inside pcibios_reset_secondary_bus() records the
> IRQ-disabled PCI_ERR_ROOT_COMMAND value into dev->saved_cap_space, so
> any subsequent pci_restore_state(dev) will leave Root Port AER interrupts
> disabled.  And if host->reset_root_port() fails, dev->state_saved is left set with
> the broken state, causing pci_pm_suspend_noirq_common() to skip saving state
> and pci_prepare_to_sleep() on system suspend.
> 

I will send a v2 to fix the issue found by Sashiko

[Li,Rongqing] 


> --
> Sashiko AI
> review · https://sashiko.dev/#/patchset/20261110053348.2419-2-lirongqing
> @baidu.com?part=1