Re: [PATCH v1 1/2] dt-bindings: usb: add TUSB73x0 PCIe

[Francesco Dolcini <francesco@dolcini.it>]

Hello Conor,

On Fri, Oct 04, 2024 at 04:23:18PM +0100, Conor Dooley wrote:
> On Fri, Oct 04, 2024 at 02:45:20PM +0200, Francesco Dolcini wrote:
> > From: Parth Pancholi <parth.pancholi@toradex.com>
> > 
> > Add device tree bindings for TI's TUSB73x0 PCIe-to-USB 3.0 xHCI
> > host controller. The controller supports software configuration
> > through PCIe registers, such as controlling the PWRONx polarity
> > via the USB control register (E0h).
> > 
> > Similar generic PCIe-based bindings can be found as qcom,ath11k-pci.yaml
> > as an example.
> > 
> > Datasheet: https://www.ti.com/lit/ds/symlink/tusb7320.pdf
> > Signed-off-by: Parth Pancholi <parth.pancholi@toradex.com>
> > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> > ---
> >  .../bindings/usb/ti,tusb73x0-pci.yaml         | 60 +++++++++++++++++++
> >  1 file changed, 60 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/ti,tusb73x0-pci.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/ti,tusb73x0-pci.yaml b/Documentation/devicetree/bindings/usb/ti,tusb73x0-pci.yaml
> > new file mode 100644
> > index 000000000000..bcb619b08ad3
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/ti,tusb73x0-pci.yaml
> > @@ -0,0 +1,60 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/ti,tusb73x0-pci.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: TUSB73x0 USB 3.0 xHCI Host Controller (PCIe)
> > +
> > +maintainers:
> > +  - Francesco Dolcini <francesco.dolcini@toradex.com>
> > +
> > +description:
> > +  TUSB73x0 USB 3.0 xHCI Host Controller via PCIe x1 Gen2 interface.
> > +  The TUSB7320 supports up to two downstream ports, the TUSB7340 supports up
> > +  to four downstream ports.
> > +
> > +properties:
> > +  compatible:
> > +    const: pci104C,8241
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  ti,tusb7320-pwron-polarity-invert:
> 
> To me, "polarity-invert" makes less sense than calling this "active-high"
> making the property a flag. active-low would then be the case where the
> property is not provided. Given you don't make the property required,
> what you've got here is effectively a flag anyway.

We had the same doubt when deciding which property name to propose, looking
at the existing bindings it seemed that "polarity-invert" was more common.

FTR the datasheet explicetly name the signals with a # suffix (PWRON1#,
PWRON2#, ...), they are defined as active-low by default.

With that said, if we prefer to have `ti,tusb7320-pwron-active-high`, I am 100%
good with it.

Francesco