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 <[email protected]>
---
.../devicetree/bindings/net/ti,dp83867.yaml | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
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
--
2.31.1
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 <[email protected]>
> ---
> .../devicetree/bindings/net/ti,dp83867.yaml | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
Reviewed-by: Rob Herring <[email protected]>
On Mon, Jun 06, 2022 at 10:22:18PM +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 <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Andrew