RE: [PATCH 2/2] PCI: amd-mdb: Add amd,versal2-cpm6-host compatible

[Musham, Sai Krishna]

[Public]

Hi Krzysztof/Manivannan,

> -----Original Message-----
> From: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> Sent: Saturday, April 4, 2026 8:46 AM
> To: Musham, Sai Krishna <sai.krishna.musham@xxxxxxx>
> Cc: bhelgaas@xxxxxxxxxx; lpieralisi@xxxxxxxxxx; kw@xxxxxxxxx;
> robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
> cassel@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; Simek, Michal <michal.simek@xxxxxxx>;
> Gogada, Bharat Kumar <bharat.kumar.gogada@xxxxxxx>; Havalige,
> Thippeswamy <thippeswamy.havalige@xxxxxxx>
> Subject: Re: [PATCH 2/2] PCI: amd-mdb: Add amd,versal2-cpm6-host
> compatible
>
> On Thu, Apr 02, 2026 at 11:30:06PM +0530, Sai Krishna Musham wrote:
> > Add "amd,versal2-cpm6-host" to the OF match table of the AMD MDB PCIe
> > host controller driver.
> >
> > The Versal2 CPM6 host controller is DesignWare-based and supports
> > PCIe Gen6 operation at up to 64 GT/s per lane. It is currently
> > handled by the same driver and match data (NULL) as the existing
> > MDB host controller, but CPM6 uses a newer IP revision and differs
> > in legacy INTx register offsets.
> >
> > Use a separate compatible to allow CPM6-specific handling once legacy
> > interrupt support is validated.
> >
> > Signed-off-by: Sai Krishna Musham <sai.krishna.musham@xxxxxxx>
> > ---
> >  drivers/pci/controller/dwc/pcie-amd-mdb.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > index 3c6e837465bb..325bf7aad657 100644
> > --- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > +++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > @@ -511,6 +511,9 @@ static const struct of_device_id
> amd_mdb_pcie_of_match[] = {
> >     {
> >             .compatible = "amd,versal2-mdb-host",
> >     },
> > +   {
> > +           .compatible = "amd,versal2-cpm6-host",
>
> As Krzysztof commented, if the PCIe IP is compatible with an older version,
> 'amd,versal2-mdb-host' in this case, you don't need to add the new
> compatible
> to the driver. Just document the new one with fallback to the old compatible
> in
> the binding and let the driver work with the old compatible.
>

Thanks for the review. CPM6 uses a different DesignWare IP revision and
has differences in legacy interrupt register offsets. I will send a follow-up
patch to address these.

> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்


Regards,
Sai Krishna