RE: [PATCH v2 1/2] dt-bindings: PCI: amd-mdb: Add `reset-gpios` property to example device tree

[Musham, Sai Krishna]

[AMD Official Use Only - AMD Internal Distribution Only]

Hi Manivannan,

> -----Original Message-----
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Sent: Friday, May 2, 2025 8:55 PM
> 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 v2 1/2] dt-bindings: PCI: amd-mdb: Add `reset-gpios` property
> to example device tree
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Tue, Apr 29, 2025 at 02:30:45PM +0530, Sai Krishna Musham wrote:
> > Add `reset-gpios` property to the example device tree node for
> > GPIO-based handling of the PCIe Root Port (RP) PERST# signal.
> >
> > Signed-off-by: Sai Krishna Musham <sai.krishna.musham@xxxxxxx>
> > ---
> > Changes in v2:
> > - Update commit message
> > ---
> >  Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml | 2
> > ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > index 43dc2585c237..e6117d326279 100644
> > --- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > +++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > @@ -87,6 +87,7 @@ examples:
> >    - |
> >      #include <dt-bindings/interrupt-controller/arm-gic.h>
> >      #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/gpio/gpio.h>
> >
> >      soc {
> >          #address-cells = <2>;
> > @@ -112,6 +113,7 @@ examples:
> >              #size-cells = <2>;
> >              #interrupt-cells = <1>;
> >              device_type = "pci";
> > +            reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
>
> You should move this property to the PCI bridge node where it belongs to. We
> identified this issue of stuffing bridge specific properties to the controller node
> recently (yeah very late though), but since this controller doesn't have any bridge
> specific properties till now, I'd like it to do the right thing.
>
> So please refer the STM32 sereies on how to do it [1][2]. On the driver side, you
> specifically need to implement an equivalent of stm32_pcie_parse_port() in that
> patch that parses the bridge node(s) for these properties.
>
> - Mani
>
> [1] https://lore.kernel.org/linux-pci/20250423090119.4003700-2-
> christian.bruel@xxxxxxxxxxx/
> [2] https://lore.kernel.org/linux-pci/20250423090119.4003700-3-
> christian.bruel@xxxxxxxxxxx/
>

Thanks for the reference, I have moved reset-gpios to PCI bridge node, will send
it in next patch.

> --
> மணிவண்ணன் சதாசிவம்

Regards,
Sai Krishna