Re: [PATCH v4 7/7] PCI: rzg3s-host: Use common pci_host_common_link_train_delay() helper

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The mandatory PCIe link training delay is skipped when the 'max-link-speed' device tree property is omitted.
--

commit 66a7457779d07490b3340e0c36c8ac63f1f0a84f
Author: Hans Zhang <18255117159@163.com>

PCI: rzg3s-host: Use common pci_host_common_link_train_delay() helper

This commit replaces an unconditional 100ms msleep with the
pci_host_common_link_train_delay() helper. The delay is now only applied
when max_link_speed is greater than 2.

> diff --git a/drivers/pci/controller/pcie-rzg3s-host.c b/drivers/pci/controller/pcie-rzg3s-host.c
> --- a/drivers/pci/controller/pcie-rzg3s-host.c
> +++ b/drivers/pci/controller/pcie-rzg3s-host.c
[ ... ]
> @@ -1663,7 +1664,7 @@ rzg3s_pcie_host_setup(struct rzg3s_pcie_host *host,
>  	if (ret)
>  		dev_info(dev, "Failed to set max link speed\n");
>  
> -	msleep(PCIE_RESET_CONFIG_WAIT_MS);
> +	pci_host_common_link_train_delay(host->max_link_speed);

Could this regression skip the mandatory link training delay if the
max-link-speed device tree property is omitted?

If the property is missing, of_pci_get_max_link_speed() returns a negative
error code like -EINVAL, which gets stored in host->max_link_speed.

When rzg3s_pcie_set_max_link_speed() runs, it ignores negative values and
uses the hardware's native capability to configure the link, which could be
Gen3 or Gen4. However, host->max_link_speed is not updated to reflect this
actual link speed.

Because pci_host_common_link_train_delay() takes an int, passing the
negative error code causes the condition to evaluate to false:

drivers/pci/controller/pci-host-common.h:pci_host_common_link_train_delay() {
        if (max_link_speed > 2)
                msleep(PCIE_RESET_CONFIG_WAIT_MS);
}

This skips the 100ms delay even for Gen3+ links, which could cause
enumeration failures for downstream devices.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260518004246.1384532-1-18255117159@163.com?part=7