Rob, On Mon, May 7, 2018 at 8:53 AM, Rob Herring <robh@xxxxxxxxxx> wrote: > 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 I had this same comment in the post of v4. See <https://patchwork.kernel.org/patch/10314923/>. Specifically, I said: > Perhaps just make this a boolean property. If it exists then you get > the non-default case. AKA: if the default is full bit width, then > you'd allow a boolean property "qcom,preemphasis-half-width" to > override. If the default is half bit width then you'd allow > "qcom,preemphasis-full-width" to override. Manu replied: > Default property value for an SOC is specified in driver and could vary from > soc to soc. Hence, from board devicetree for different SOCs we might need > to select separate widths overriding default driver values. > Alternative is to have two bool properties each for half and full-width. Did > you actually mean that? IMHO given Manu's argument it seems fine to specify it the way he did. Please advise if you agree or disagree. -Doug -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
