usb: dwc3: add Tx de-emphasis quirk
This patch adds Tx de-emphasis quirk, and the Tx de-emphasis value is
configurable according to PIPE3 specification.
Value Description
0 -6dB de-emphasis
1 -3.5dB de-emphasis
2 No de-emphasis
3 Reserved
It can be configured on DT or platform data.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index 1ecc333..b724b2e 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -29,6 +29,9 @@
- snps,lfps_filter_quirk: when set core will filter LFPS reception.
- snps,rx_detect_poll_quirk: when set core will disable a 400us delay to start
Polling LFPS after RX.Detect.
+ - snps,tx_de_emphasis_quirk: when set core will set Tx de-emphasis value.
+ - snps,tx_de_emphasis: the value driven to the PHY is controlled by the
+ LTSSM during USB3 Compliance mode.
This is usually a subnode to DWC3 glue to which it is connected.