Re: [PATCH 2/2] dt-bindings: usb: USB2512x boost value for up- and downstream ports

[Rob Herring <robh@kernel.org>]

On Fri, Mar 11, 2022 at 12:09:42PM +0000, Neumann, Bastian wrote:
> This patch adds devicetree documentation for signal boosting properties.
> 
> Signed-off-by: Bastian Neumann <bastian.neumann@dentsplysirona.com>
> ---
>  .../devicetree/bindings/usb/usb251xb.txt      | 22 +++++++++++++++++++
>  1 file changed, 22 insertions(+)

A popular feature all the sudden. Which one are we supposed to apply? 
This one or this[1]?

Rob

[1] https://lore.kernel.org/all/20220306184720.5350-1-tomm.merciai@gmail.com/

> 
> diff --git a/Documentation/devicetree/bindings/usb/usb251xb.txt b/Documentation/devicetree/bindings/usb/usb251xb.txt
> index 1a934eab175e..538ae49fc31d 100644
> --- a/Documentation/devicetree/bindings/usb/usb251xb.txt
> +++ b/Documentation/devicetree/bindings/usb/usb251xb.txt
> @@ -68,6 +68,26 @@ Optional properties :
>   - swap-dx-lanes : Specifies the ports which will swap the differential-pair
>         (D+/D-), default is not-swapped.
> 
> +Electrical signal boosting
> +The controller supplies a "boosting" functionality to drive up the USB
> +electrical signals. This could result in non-USB compliant parameters
> +(one example would be J/K level test). This should be <0x00> unless specific
> +implementation issues requiew additional signal boosting to correct for deraded
> +USB signaling levels:
> + - <0x00> : Normal electrical drive strength (no boost)
> + - <0x01> : Elevated drive strength low (~4% boost)
> + - <0x02> : Elevated drive strength medium (~8% boost)
> + - <0x03> : Elevated drive strength high (~12% boost)
> +
> + - boost-up : USB electrical signaling drive strength boost for upstream port.
> + - boost-1 :  USB electrical signaling drive strength boost for port 1.
> + - boost-2 :  USB electrical signaling drive strength boost for port 2.
> + - boost-3 :  USB electrical signaling drive strength boost for port 3.
> + - boost-4 :  USB electrical signaling drive strength boost for port 4.
> + - boost-5 :  USB electrical signaling drive strength boost for port 5.
> + - boost-6 :  USB electrical signaling drive strength boost for port 6.
> + - boost-7 :  USB electrical signaling drive strength boost for port 7.
> +
>  Examples:
>         usb2512b@2c {
>                 compatible = "microchip,usb2512b";
> @@ -86,4 +106,6 @@ Examples:
>                 serial = "1234567890A";
>                 /* correct misplaced usb connectors on port 1,2 */
>                 swap-dx-lanes = <1 2>;
> +               boost-up = <0x00>; /* no boost for upstream port */
> +               boost-1 = <0x02>; /* medium boost on port 1 */
>         };
> --
> 2.30.2
> 
> 
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