Re: [v4 1/4] PCI: Introduce generic capability search functions

[Hans Zhang]

On 2025/3/21 21:00, Manivannan Sadhasivam wrote:
> On Fri, Mar 21, 2025 at 06:17:07PM +0800, Hans Zhang wrote:
> > Existing controller drivers (e.g., DWC, custom out-of-tree drivers)
> > duplicate logic for scanning PCI capability lists. This creates
> > maintenance burdens and risks inconsistencies.
> >
> > To resolve this:
> >
> > 1. Add pci_generic_find_capability() and pci_generic_find_ext_capability()
> > in drivers/pci/pci.c, accepting controller-specific read functions
> > and device data as parameters.
>
> I'd reword pci_generic* as pci_host_bridge* to reflect the fact that these APIs
> are meant for host bridges.

Hi Mani,

Thanks your for reply. Will change.

> > 2. Refactor dwc_pcie_find_capability() and similar functions to utilize
> > these new generic interfaces.
>
> This is not part of this patch. So should be dropped.

Will change.

> > 3. Update out-of-tree drivers to leverage the common implementation,
> > eliminating code duplication.
>
> This also.

Will change.

> > This approach:
> > - Centralizes critical PCI capability scanning logic
> > - Allows flexible adaptation to varied hardware access methods
> > - Reduces future maintenance overhead
> > - Aligns with kernel code reuse best practices
> >
> > Tested with DWC PCIe controller and CDNS PCIe drivers.
>
> This tested info is also not required since the DWC and CDNS changes are not
> part of this patch.

Will change.

Best regards,
Hans