Re: [PATCH 2/7] dt-bindings: phy: mediatek,tphy: add property to set pre-emphasis
From: Krzysztof Kozlowski <hidden>
Date: 2022-08-31 06:03:53
Also in:
linux-arm-kernel, linux-mediatek, linux-phy, lkml
On 31/08/2022 06:00, Chunfeng Yun wrote:
On Tue, 2022-08-30 at 13:08 +0300, Krzysztof Kozlowski wrote:quoted
On 29/08/2022 05:37, Chunfeng Yun wrote:quoted
On Fri, 2022-08-26 at 09:36 +0300, Krzysztof Kozlowski wrote:quoted
On 26/08/2022 08:36, Chunfeng Yun wrote:quoted
On Tue, 2022-08-23 at 13:24 +0300, Krzysztof Kozlowski wrote:quoted
On 22/08/2022 10:07, Chunfeng Yun wrote:quoted
On Fri, 2022-08-19 at 15:15 +0300, Krzysztof Kozlowski wrote:quoted
On 19/08/2022 12:13, Chunfeng Yun wrote:quoted
Add a property to set usb2 phy's pre-emphasis. Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com> --- Documentation/devicetree/bindings/phy/mediatek,tphy.ya ml | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/devicetree/bindings/phy/mediatek,tphy.y aml b/Documentation/devicetree/bindings/phy/mediatek,tphy.y aml index 848edfb1f677..aee2f3027371 100644 --- a/Documentation/devicetree/bindings/phy/mediatek,tphy.y aml +++ b/Documentation/devicetree/bindings/phy/mediatek,tphy.y aml@@ -219,6 +219,13 @@ patternProperties: minimum: 1 maximum: 15 + mediatek,pre-emphasis: + description: + The selection of pre-emphasis (U2 phy) + $ref: /schemas/types.yaml#/definitions/uint32 + minimum: 1 + maximum: 3Instead of hard-coding register values in bindings, you should rather describe here feature/effect. If it is in units, use unit suffixes. If it is some choice, usually string enum is appropriate.How about changing description as bellow: "The level of pre-emphasis, increases one level, boosts the relative amplitudes of signal's higher frequencies components about 4.16% (U2 phy)"Still the question is what is the unit. 4.16%?No unit, it's a level value, like an index of array.So a value from register/device programming?Yesquoted
Rather a regular units should be used if that's possible. If not, this should be clearly described here, not some magical number which you encode into DTS...Ok, I'll add more descriptions.Better use logical value, e.g.https://urldefense.com/v3/__https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml*L38__;Iw!!CTRNKA9wMg0ARbw!1e-h0R_uwcaHKfKC9qYfaRWYeuWRq1sLCGy3yupNmkFyuW5s1nmRotL7Y0vFG9ETLLTA$quoted
Optional unit may be -percent or -bp, but the value 4.16% * X (X=1,2,3...)is not an exact value, they are variable in a range and dependent more factors. So I think use level value is simple enough.
Then again explain exactly what are the levels. How you wrote it last time, -bp would do the trick. Best regards, Krzysztof