On Tue, May 24, 2022 at 3:15 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> Not sure whether anybody cares about the keystone driver any more. It
> seems basically unmaintained after 57e1d8206e48 ("MAINTAINERS: move
> Murali Karicheri to credits") [1].
>
> Anyway, ks_pcie_v3_65_add_bus() [2] looks unusual to me. It's an
> .add_bus() method that is called whenever we create a new PCI bus:
>
> ks_pcie_v3_65_add_bus(...)
> {
> ks_pcie_set_dbi_mode
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 1)
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, SZ_4K - 1)
> ks_pcie_clear_dbi_mode(ks_pcie)
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, ks_pcie->app.start)
> }
>
> This seems like something that should be done when the Root Port is
> enumerated, not when we set up its secondary bus. Maybe somewhere in
> ks_pcie_host_init() or ks_pcie_config_msi_irq()?
See these commits for the reasoning:
1df793054859 PCI: dwc: Convert to use pci_host_probe()
6ab15b5e7057 PCI: dwc: keystone: Convert .scan_bus() callback to use add_bus
6e8e104d2196 PCI: Also call .add_bus() callback for root bus
The reason was to keep the initialization in the same order as when we
had the DWC specific .scan_bus() op. There's not a driver hook in
between the h/w setup and scanning devices.
> I don't think we should use .add_bus() unless it's actually something
> related to adding a bus.
I think I was inspired from how pcibios_add_bus() is (ab)used.
Rob
