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

[Richard Leitner <richard.leitner@linux.dev>]

On Fri, Mar 11, 2022 at 08:48:17AM -0600, Rob Herring wrote:
> 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]?

This seems to be a superset of the previous patchset from Tommaso.
Therefore I'd definitley vote for this one if a v2 of it [2] gets
merged (it was declined by GregKH because of the e-mail signature and
fomatting issues).

Until then I assume [1] should be applied as it represents the current
master state due to
commit 5c2b9c61ae5d (usb: usb251xb: add boost-up property support, 2022-01-28)
being already merged.

regards;rl

[2] https://lore.kernel.org/linux-usb/PH0PR17MB48482AD591AFD471637B16E28E0C9@PH0PR17MB4848.namprd17.prod.outlook.com/
> 
> 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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