Thread (23 messages) 23 messages, 4 authors, 2022-09-14

Re: [PATCH 2/7] dt-bindings: phy: mediatek,tphy: add property to set pre-emphasis

From: Krzysztof Kozlowski <hidden>
Date: 2022-08-26 06:37:05
Also in: linux-arm-kernel, linux-mediatek, linux-phy, lkml

On 26/08/2022 08:36, Chunfeng Yun wrote:
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.yaml | 7
+++++++
 1 file changed, 7 insertions(+)

diff --git
a/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
b/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
index 848edfb1f677..aee2f3027371 100644
--- a/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
+++ b/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
@@ -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: 3
Instead 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? 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...

Best regards,
Krzysztof
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