[PATCH v4 2/2] dt-bindings: usb: snps,dwc3: Add 'snps,parkmode-disable-hs-quirk' quirk

[Stanley Chang]

Add a new 'snps,parkmode-disable-hs-quirk' DT quirk to dwc3 core for
disable the high-speed parkmode.

For some USB wifi devices, if enable this feature it will reduce the
performance. Therefore, add an option for disabling HS park mode by
device-tree.

In Synopsys's dwc3 data book:
In a few high speed devices when an IN request is sent within 900ns of the
ACK of the previous packet, these devices send a NAK. When connected to
these devices, if required, the software can disable the park mode if you
see performance drop in your system. When park mode is disabled,
pipelining of multiple packet is disabled and instead one packet at a time
is requested by the scheduler. This allows up to 12 NAKs in a micro-frame
and improves performance of these slow devices.

Signed-off-by: Stanley Chang <stanley_chang@xxxxxxxxxxx>
Acked-by: Rob Herring <robh@xxxxxxxxxx>
---
 Documentation/devicetree/bindings/usb/snps,dwc3.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
index be36956af53b..45ca967b8d14 100644
--- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
+++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
@@ -232,6 +232,11 @@ properties:
       When set, all SuperSpeed bus instances in park mode are disabled.
     type: boolean
 
+  snps,parkmode-disable-hs-quirk:
+    description:
+      When set, all HighSpeed bus instances in park mode are disabled.
+    type: boolean
+
   snps,dis_metastability_quirk:
     description:
       When set, disable metastability workaround. CAUTION! Use only if you are
-- 
2.34.1