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SubjectRe: [PATCH 1/2] dt-bindings: mtd: spi-nor: Add output-driver-strength property
On Mon, Oct 04, 2021 at 01:15:28PM +0200, Alexander Stein wrote:
> From: Alexander Stein <alexander.stein@ew.tq-group.com>
>
> This property is for optimizing output voltage impedance and is
> specific to each board.
>
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> ---
> I checked Micron and Macronix datasheets. Both have similar but not
> identical supported values. Also the register locations are different.
> For those reasons I decided to specify the Ohms value directly and let
> the device specfic driver figure out if it is supported where to write
> it to.
> BTW: Are the Ohm values and the corresponding register bits standardized
> somewhere?
>
> Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> index ed590d7c6e37..7d7f20a741b5 100644
> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> @@ -72,6 +72,12 @@ properties:
> be used on such systems, to denote the absence of a reliable reset
> mechanism.
>
> + output-driver-strength:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + Output driver strength in Ohms which optimizes the impedance at Vcc/2
> + output voltage.

Use a standard unit suffix.

Though, specifying 'drive strength' in ohms rather than amps is a bit
strange.

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