linux-kernel - Re: [PATCH v1 1/2] dt-bindings: PCI: ti,j721e-pci-host: Add optional regulator supplies

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Message-ID: <2c3e4bdefb306dc89c15bebc549d854ea2b4cc32.camel@gmail.com>
Date: Mon, 27 Oct 2025 23:22:26 +0000
From: Vitor Soares <ivitro@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi
 <lpieralisi@...nel.org>, Krzysztof Wilczyński
 <kwilczynski@...nel.org>, Manivannan Sadhasivam <mani@...nel.org>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
 Dooley <conor+dt@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Vitor Soares <vitor.soares@...adex.com>, linux-pci@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: PCI: ti,j721e-pci-host: Add
 optional regulator supplies

Hi Krzysztof,

Thank you for the feedback.

On Mon, 2025-10-20 at 13:14 +0200, Krzysztof Kozlowski wrote:
> On Tue, Oct 14, 2025 at 12:25:48PM +0100, Vitor Soares wrote:
> > From: Vitor Soares <vitor.soares@...adex.com>
> > 
> > Add optional regulator supply properties for PCIe endpoints on TI SoCs.
> > Some boards provide dedicated regulators for PCIe devices, such as
> > 1.5V (miniPCIe), 3.3V (common for M.2 or miniPCIe), or 12V
> > (for high-power devices). These supplies are now described as optional
> > properties to allow the driver to control endpoint power where supported.
> 
> Last sentence is completely redundant. Please do not describe DT, we
> all can read the patch. Driver is irrelevant here.
> 
> 
Ack, I will remove last sentence.

> 
> How you described here and in descriptions, suggests these are rather
> port properties, not the controller.

You are right - these supplies power the PCIe slot/connector, not the controller
itself. However, as per my understanding, the current kernel practice is to
place slot supplies in the root complex node rather than the endpoint node. as
seen in e.g.:
- imx6q-pcie.yaml
- rockchip-dw-pcie.yaml
- rcar-pci-host.yaml

This seems consistent with those existing bindings, but please let me know if
I’m overlooking something specific to this case.

> 
> > 
> > Signed-off-by: Vitor Soares <vitor.soares@...adex.com>
> > ---
> >  .../devicetree/bindings/pci/ti,j721e-pci-host.yaml | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/pci/ti,j721e-pci-host.yaml
> > b/Documentation/devicetree/bindings/pci/ti,j721e-pci-host.yaml
> > index c704099f134b..a20b03406448 100644
> > --- a/Documentation/devicetree/bindings/pci/ti,j721e-pci-host.yaml
> > +++ b/Documentation/devicetree/bindings/pci/ti,j721e-pci-host.yaml
> > @@ -110,6 +110,18 @@ properties:
> >        interrupts:
> >          maxItems: 1
> >  
> > +  vpcie1v5-supply:
> 
> How is it called in this device datasheet (not the board schematics)?

The TI SoC datasheet describes the controller interface but doesn’t define these
external supply rails - they are board-level regulators specific to the slot.

> 
> > +    description: 1.5V regulator used to power PCIe interfaces,
> > +                 typically present on miniPCIe slots.
> 
> Best regards,
> Krzysztof
> 

Best regards,
Vitor Soares