Re: [PATCH v2 1/2] PCI: rzg3s-host: Use pci_generic_config_write() for the root bus

[Wolfram Sang]

On Wed, Dec 17, 2025 at 01:15:09PM +0200, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> 
> The Renesas RZ/G3S host controller allows writing to read-only PCIe
> configuration registers when the RZG3S_PCI_PERM_CFG_HWINIT_EN bit is set in
> the RZG3S_PCI_PERM register. However, callers of struct pci_ops::write
> expect the semantics defined by the PCIe specification, meaning that writes
> to read-only registers must not be allowed.
> 
> The previous custom struct pci_ops::write implementation for the root bus
> temporarily enabled write access before calling pci_generic_config_write().
> This breaks the expected semantics.
> 
> Remove the custom implementation and simply use pci_generic_config_write().
> 
> Along with this change, the updates of the PCI_PRIMARY_BUS,
> PCI_SECONDARY_BUS, and PCI_SUBORDINATE_BUS registers were moved so that
> they no longer depends on the RZG3S_PCI_PERM_CFG_HWINIT_EN bit in the
> RZG3S_PCI_PERM_CFG register, since these registers are R/W.
> 
> Fixes: 7ef502fb35b2 ("PCI: Add Renesas RZ/G3S host controller driver")
> Suggested-by: Bjorn Helgaas <helgaas@xxxxxxxxxx>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>

Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>

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