This patch adds devicetree documentation for signal boosting properties.
Signed-off-by: Bastian Neumann <bastian.neumann@xxxxxxxxxxxxxxxxxx>
---
.../devicetree/bindings/usb/usb251xb.txt | 22 +++++++++++++++++++
1 file changed, 22 insertions(+)
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
-----------------------------------------------------------------------------------------------------------
Sirona Dental Systems GmbH
Sitz der Gesellschaft / registered address: Fabrikstraße 31, 64625 Bensheim
Registergericht / court of registry: Amtsgericht Darmstadt, HRB 24948
Geschäftsführer / Managing Director: Dr. Cord Stähler, Jan Siefert, Rainer Raschke
Aufsichtsratsvorsitzender / Chairman of the Supervisory Board: Dr. Alexander Voelcker
-----------------------------------------------------------------------------------------------------------
Diese E-Mail ist ausschliesslich fuer den angesprochenen Adressaten
bestimmt und kann vertrauliche Informationen beinhalten.
--
This e-mail is intended only for the designated recipient(s). It may
contain confidential or proprietary information.
------------------------------------------------------------------------------------------------------------
