Re: [PATCH v5 6/7] dt-bindings: phy-qcom-usb2: Add support to override tuning values

From: Rob Herring
Date: Mon May 07 2018 - 11:53:21 EST


On Thu, May 03, 2018 at 02:36:13AM +0530, Manu Gautam wrote:
> To improve eye diagram for PHYs on different boards of same SOC,
> some parameters may need to be changed. Provide device tree
> properties to override these from board specific device tree
> files. While at it, replace "qcom,qusb2-v2-phy" with compatible
> string for USB2 PHY on sdm845 which was earlier added for
> sdm845 only.
>
> Signed-off-by: Manu Gautam <mgautam@xxxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/phy/qcom-qusb2-phy.txt | 23 +++++++++++++-
> include/dt-bindings/phy/phy-qcom-qusb2.h | 37 ++++++++++++++++++++++
> 2 files changed, 59 insertions(+), 1 deletion(-)
> create mode 100644 include/dt-bindings/phy/phy-qcom-qusb2.h
>
> diff --git a/Documentation/devicetree/bindings/phy/qcom-qusb2-phy.txt b/Documentation/devicetree/bindings/phy/qcom-qusb2-phy.txt
> index 42c9742..03025d9 100644
> --- a/Documentation/devicetree/bindings/phy/qcom-qusb2-phy.txt
> +++ b/Documentation/devicetree/bindings/phy/qcom-qusb2-phy.txt
> @@ -6,7 +6,7 @@ QUSB2 controller supports LS/FS/HS usb connectivity on Qualcomm chipsets.
> Required properties:
> - compatible: compatible list, contains
> "qcom,msm8996-qusb2-phy" for 14nm PHY on msm8996,
> - "qcom,qusb2-v2-phy" for QUSB2 V2 PHY.
> + "qcom,sdm845-qusb2-phy" for 10nm PHY on sdm845.
>
> - reg: offset and length of the PHY register set.
> - #phy-cells: must be 0.
> @@ -27,6 +27,27 @@ Optional properties:
> tuning parameter value for qusb2 phy.
>
> - qcom,tcsr-syscon: Phandle to TCSR syscon register region.
> + - qcom,imp-res-offset-value: It is a 6 bit value that specifies offset to be
> + added to PHY refgen RESCODE via IMP_CTRL1 register. It is a PHY
> + tuning parameter that may vary for different boards of same SOC.
> + This property is applicable to only QUSB2 v2 PHY (sdm845).
> + - qcom,hstx-trim-value: It is a 4 bit value that specifies tuning for HSTX
> + output current.
> + Possible range is - 15mA to 24mA (stepsize of 600 uA).
> + See dt-bindings/phy/phy-qcom-qusb2.h for applicable values.
> + This property is applicable to only QUSB2 v2 PHY (sdm845).
> + Default value is 22.2mA for sdm845.
> + - qcom,preemphasis-level: It is a 2 bit value that specifies pre-emphasis level.
> + Possible range is 0 to 15% (stepsize of 5%).
> + See dt-bindings/phy/phy-qcom-qusb2.h for applicable values.
> + This property is applicable to only QUSB2 v2 PHY (sdm845).
> + Default value is 10% for sdm845.
> +- qcom,preemphasis-width: It is a 1 bit value that specifies how long the HSTX
> + pre-emphasis (specified using qcom,preemphasis-level) must be in
> + effect. Duration could be half-bit of full-bit.

s/of/or/

But I'd just make this a boolean instead: qcom,preemphasis-half-bit

> + See dt-bindings/phy/phy-qcom-qusb2.h for applicable values.
> + This property is applicable to only QUSB2 v2 PHY (sdm845).
> + Default value is full-bit width for sdm845.