Re: [PATCH 1/3] PCI: dwc: Add support for vendor specific capability search

[Vidya Sagar]

On 5/22/2021 5:01 AM, Krzysztof Wilczyński wrote:
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>
>
> Hi Shradha,
>
> [...]
> > +u16 dw_pcie_find_vsec_capability(struct dw_pcie *pci, u8 vsec_cap)
> > +{
> > +     u16 vsec = 0;
> > +     u32 header;
> > +
> > +     while ((vsec = dw_pcie_find_next_ext_capability(pci, vsec,
> > +                                     PCI_EXT_CAP_ID_VNDR))) {
> > +             header = dw_pcie_readl_dbi(pci, vsec + PCI_VNDR_HEADER);
> > +             if (PCI_VNDR_HEADER_ID(header) == vsec_cap)
> > +                     return vsec;
> > +     }
> > +
> > +     return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(dw_pcie_find_vsec_capability);
>
> A small question as I am curious: why not use pci_find_vsec_capability()
> here?  The implementation looks very similar, which is why I am asking,
> but it might be that I am missing something, and for that I apologise in
> advance.
pci_find_vsec_capability() expects struct pci_dev * which we get only 
after enumeration is done. In the current scenario, we are still in 
pre-link up phase and don't have struct pci_dev * yet, hence this 
implementation, right Shradha??

>          Krzysztof