Re: [PATCH net-next v2 3/4] dt-bindings: net: Add RGMII internal delay for DP83869

[Dan Murphy]

Andrew

On 5/20/20 10:28 AM, Dan Murphy wrote:
> Andrew
>
> On 5/20/20 8:56 AM, Andrew Lunn wrote:
> > On Wed, May 20, 2020 at 07:18:34AM -0500, Dan Murphy wrote:
> > > Add the internal delay values into the header and update the binding
> > > with the internal delay properties.
> > >
> > > Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
> > > ---
> > > Â .../devicetree/bindings/net/ti,dp83869.yamlÂÂÂ | 16 ++++++++++++++++
> > > Â include/dt-bindings/net/ti-dp83869.hÂÂÂÂÂÂÂÂÂÂ | 18 
> > > ++++++++++++++++++
> > > Â 2 files changed, 34 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/net/ti,dp83869.yaml 
> > > b/Documentation/devicetree/bindings/net/ti,dp83869.yaml
> > > index 5b69ef03bbf7..344015ab9081 100644
> > > --- a/Documentation/devicetree/bindings/net/ti,dp83869.yaml
> > > +++ b/Documentation/devicetree/bindings/net/ti,dp83869.yaml
> > > @@ -64,6 +64,20 @@ properties:
> > >  Operational mode for the PHY. If this is not set then the 
> > > operational
> > > ÂÂÂÂÂÂÂÂ mode is set by the straps. see dt-bindings/net/ti-dp83869.h 
> > > for values
> > > Â +Â ti,rx-internal-delay:
> > > +ÂÂÂ $ref: /schemas/types.yaml#definitions/uint32
> > > +ÂÂÂ description: |
> > > +ÂÂÂÂÂ RGMII Receive Clock Delay - see dt-bindings/net/ti-dp83869.h
> > > +ÂÂÂÂÂ for applicable values. Required only if interface type is
> > > +ÂÂÂÂÂ PHY_INTERFACE_MODE_RGMII_ID or PHY_INTERFACE_MODE_RGMII_RXID.
> > Hi Dan
> >
> > Having it required with PHY_INTERFACE_MODE_RGMII_ID or
> > PHY_INTERFACE_MODE_RGMII_RXID is pretty unusual. Normally these
> > properties are used to fine tune the delay, if the default of 2ns does
> > not work.
>
> Also if the MAC phy-mode is configured with RGMII-ID and no internal 
> delay values defined wouldn't that be counter intuitive?
>
> The driver will error out if the RGMII-ID is used and there was no 
> internal delay defined for either rx or tx making either one required.
>
> The MAC node needs to indicate to use the internal delay for RGMII 
> other wise the driver should ignore the internal delay programming as 
> these internal delays are not applicable to SGMII or MII modes. The 
> RGMII mode can be used if the default 2ns delay is acceptable.
>
> Thus why we are documenting in the binding when the internal delay is 
> required as putting these under "required" is not correct.
>
> Dan
This is also the same for the DP83867 PHY as that PHY and the 83869 have 
a few identical features like internal delay, WoL and downshifting.

Dan


> > ÂÂÂÂ Andrew