RE: [PATCH 07/11] dt-bindings: spi: spi-nxp-fspi: add a new property nxp,fspi-dll-slvdly

[Han Xu <han.xu@nxp.com>]

>-----Original Message-----
>From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>Sent: Tuesday, July 5, 2022 5:37 AM
>To: Bough Chen <haibo.chen@nxp.com>; ashish.kumar@nxp.com;
>yogeshgaur.83@gmail.com; broonie@kernel.org; robh+dt@kernel.org;
>krzysztof.kozlowski+dt@linaro.org; Han Xu <han.xu@nxp.com>;
>singh.kuldeep87k@gmail.com; tudor.ambarus@microchip.com; p.yadav@ti.com;
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>Cc: linux-spi@vger.kernel.org; linux-kernel@vger.kernel.org;
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>Subject: Re: [PATCH 07/11] dt-bindings: spi: spi-nxp-fspi: add a new property
>nxp,fspi-dll-slvdly
>
>On 05/07/2022 12:28, Bough Chen wrote:
>>> -----Original Message-----
>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>> Sent: 2022年7月5日 17:48
>>> To: Bough Chen <haibo.chen@nxp.com>; ashish.kumar@nxp.com;
>>> yogeshgaur.83@gmail.com; broonie@kernel.org; robh+dt@kernel.org;
>>> krzysztof.kozlowski+dt@linaro.org; Han Xu <han.xu@nxp.com>;
>>> singh.kuldeep87k@gmail.com; tudor.ambarus@microchip.com;
>>> p.yadav@ti.com; michael@walle.cc; miquel.raynal@bootlin.com;
>>> richard@nod.at; vigneshr@ti.com; shawnguo@kernel.org;
>>> s.hauer@pengutronix.de; kernel@pengutronix.de
>>> Cc: linux-spi@vger.kernel.org; linux-kernel@vger.kernel.org;
>>> devicetree@vger.kernel.org; linux-mtd@lists.infradead.org;
>>> festevam@gmail.com; dl-linux-imx <linux-imx@nxp.com>;
>>> linux-arm-kernel@lists.infradead.org; zhengxunli@mxic.com.tw
>>> Subject: Re: [PATCH 07/11] dt-bindings: spi: spi-nxp-fspi: add a new
>>> property nxp,fspi-dll-slvdly
>>>
>>> On 05/07/2022 11:11, haibo.chen@nxp.com wrote:
>>>> From: Haibo Chen <haibo.chen@nxp.com>
>>>>
>>>> Add one optional property nxp,fspi-dll-slvdly
>>>>
>>>> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
>>>> ---
>>>>  Documentation/devicetree/bindings/spi/spi-nxp-fspi.yaml | 6 ++++++
>>>>  1 file changed, 6 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/spi/spi-nxp-fspi.yaml
>>> b/Documentation/devicetree/bindings/spi/spi-nxp-fspi.yaml
>>>> index 1b552c298277..6bd61565686a 100644
>>>> --- a/Documentation/devicetree/bindings/spi/spi-nxp-fspi.yaml
>>>> +++ b/Documentation/devicetree/bindings/spi/spi-nxp-fspi.yaml
>>>> @@ -45,6 +45,12 @@ properties:
>>>>        - const: fspi_en
>>>>        - const: fspi
>>>>
>>>> +  nxp,fspi-dll-slvdly:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description: |
>>>> +      Specify the DLL slave line delay value.
>>>
>>> What are the units?
>>
>> Do you mean here need to give more detail explain about this properity?
>>
>> How about change like this?
>>    Specify the DLL slave line delay value. The delay target for slave delay line is:
>((nxp,fspi-dll-slvdly+1) * 1/32 * clock cycle of reference clock (serial root clock).
>
>This would be good.
>
>> The range of this value is 0~16.
>
>This needs to go to schema instead as "maximum: 16".
>
>But still the question is - what are the units used in this "delay"? ms? us?

HI Krzysztof,

According to the formula, the range should be 0~15, 16 should do nothing or no delay.

The unit should be clock phase. In other words, the delay can be in range of 1/32~1/2 clock cycle.


>
>Best regards,
>Krzysztof
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