On 14/03/2022 04:29, Pavan Kondeti wrote:

Hi Krzysztof,

On Thu, Mar 03, 2022 at 04:59:22PM +0100, Krzysztof Kozlowski wrote:

quoted

On 03/03/2022 07:13, Sandeep Maheswaram wrote:

quoted

Add device tree bindings for SNPS phy tuning parameters.

Signed-off-by: Sandeep Maheswaram <redacted>
---
 .../bindings/phy/qcom,usb-snps-femto-v2.yaml       | 125 +++++++++++++++++++++
 1 file changed, 125 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml b/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml
index 0dfe691..227c097 100644
--- a/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml
+++ b/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml

@@ -50,6 +50,131 @@ properties:
   vdda33-supply:
     description: phandle to the regulator 3.3V supply node.
 
+  qcom,hs-disconnect:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      This adjusts the voltage level for the threshold used to
+      detect a disconnect event at the host. Possible values are.

':', instead of full stop.

quoted

+      7 -> +21.56%
+      6 -> +17.43%
+      5 -> +13.32%
+      4 -> +9.73%
+      3 -> +6.3
+      2 -> +3.17%
+      1 -> 0, Design default%

Use "default:" instead. Here and in other places.

quoted

+      0 -> -2.72%

In current form this should be an enum... but actually current form is
wrong. You should not store register values in DT. What if next version
of hardware has a different meaning of these values?

Instead, you should store here meaningful values, not register values.

Thanks for the feedback.

The values in % really makes the tuning easy. People look at the eye diagram
and decided whether to increase/decrease the margin. The absolute values
may not be that useful. All we need is an "adjustment" here. The databook
it self does not give any absolute values.

I agree to the "enum" suggestion which we have been following for the
qusb2 driver already. 

The values have not changed in the last 5 years for this hardware block, so
defining enums for the % values would be really helpful. 

I did not say you cannot store here percentages. Quite opposite - store
here the percentages. Just do not store register value. No. Please read
my comment again - meaningful values are needed.


Best regards,
Krzysztof

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