Re: Query regarding the use of pcie-designware-plat.c file

[Vidya Sagar]

Bjorn / Lorenzo,
Could you please comment on the options proposed by Thierry?

- Vidya Sagar

On 6/9/2021 3:19 PM, Thierry Reding wrote:
> On Wed, Jun 09, 2021 at 10:56:48AM +0530, Vidya Sagar wrote:
> > On 6/9/2021 2:47 AM, Gustavo Pimentel wrote:
> > > External email: Use caution opening links or attachments
> > >
> > >
> > > Hi Vidya,
> > >
> > > The pcie-designware-plat.c is the driver for the Synopsys PCIe RC IP
> > > prototype.
> > Thanks for the info Gustavo.
> > But, I don't see any DT file having only "snps,dw-pcie" compatibility
> > string. All the DT files that have "snps,dw-pci" compatibility string also
> > have their platform specific compatibility string and their respective host
> > controller drivers. Also, it is the platform specific compatibility string
> > that is used for binding purpose with their respective drivers and not the
> > "snps,dw-pcie". So, wondering when will pcie-designware-plat.c be used as
> > there is not DT file which has only "snps,dw-pcie" as the compatibility
> > string.
>
> Sounds to me like we have two options:
>
>    1. If there's indeed real hardware that's identified by the existing
>       "snps,dw-pcie" compatible string, then it's wrong for other devices
>       to list that in their compatible string because they are likely not
>       compatible with that (i.e. they might be from a register point of
>       view, but at least from an integration point of view they usually
>       differ).
>
>    2. If "snps,dw-pcie" is meant to describe the fact that these are all
>       based off the same IP but may be differently integrated, then there
>       should be no driver matching on that compatible string.
>
> Option 2 is not very robust because somebody could easily add a matching
> driver at some point in the future. Also, if we don't match on a
> compatible string there's not a lot of use in listing it in DT in the
> first place.
>
> So I think option 1 would be preferred.
>
> Thierry