| Message ID | 20220606202220.1670714-2-linux@rasmusvillemoes.dk |
|---|---|
| State | Accepted |
| Commit | ab1e9de84aff0ca897dee5e4d6692ff46788697b |
| Headers | show |
| Series | net: phy: dp83867: add binding and support for io_impedance_ctrl nvmem cell | expand |
On Mon, 06 Jun 2022 22:22:18 +0200, Rasmus Villemoes wrote: > We have a board where measurements indicate that the current three > options - leaving IO_IMPEDANCE_CTRL at the (factory calibrated) reset > value or using one of the two boolean properties to set it to the > min/max value - are too coarse. > > There is no documented mapping from the 32 possible values of the > IO_IMPEDANCE_CTRL field to values in the range 35-70 ohms, and the > exact mapping is likely to vary from chip to chip. So add a DT binding > for an nvmem cell which can be populated during production with a > value suitable for each specific board. > > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> > --- > .../devicetree/bindings/net/ti,dp83867.yaml | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > Reviewed-by: Rob Herring <robh@kernel.org>
diff --git a/Documentation/devicetree/bindings/net/ti,dp83867.yaml b/Documentation/devicetree/bindings/net/ti,dp83867.yaml index 047d757e8d82..76ff08a477ba 100644 --- a/Documentation/devicetree/bindings/net/ti,dp83867.yaml +++ b/Documentation/devicetree/bindings/net/ti,dp83867.yaml @@ -31,6 +31,16 @@ properties: reg: maxItems: 1 + nvmem-cells: + maxItems: 1 + description: + Nvmem data cell containing the value to write to the + IO_IMPEDANCE_CTRL field of the IO_MUX_CFG register. + + nvmem-cell-names: + items: + - const: io_impedance_ctrl + ti,min-output-impedance: type: boolean description: | @@ -42,9 +52,11 @@ properties: description: | MAC Interface Impedance control to set the programmable output impedance to a maximum value (70 ohms). - Note: ti,min-output-impedance and ti,max-output-impedance are mutually - exclusive. When both properties are present ti,max-output-impedance - takes precedence. + Note: Specifying an io_impedance_ctrl nvmem cell or one of the + ti,min-output-impedance, ti,max-output-impedance properties + are mutually exclusive. If more than one is present, an nvmem + cell takes precedence over ti,max-output-impedance, which in + turn takes precedence over ti,min-output-impedance. tx-fifo-depth: $ref: /schemas/types.yaml#/definitions/uint32
We have a board where measurements indicate that the current three options - leaving IO_IMPEDANCE_CTRL at the (factory calibrated) reset value or using one of the two boolean properties to set it to the min/max value - are too coarse. There is no documented mapping from the 32 possible values of the IO_IMPEDANCE_CTRL field to values in the range 35-70 ohms, and the exact mapping is likely to vary from chip to chip. So add a DT binding for an nvmem cell which can be populated during production with a value suitable for each specific board. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- .../devicetree/bindings/net/ti,dp83867.yaml | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)