[PATCH v2 7/9] dt-bindings: spi: mtk-snfi: Add read latch latency property

Krzysztof Kozlowski krzysztof.kozlowski at linaro.org
Thu Dec 8 00:46:26 PST 2022

On 08/12/2022 02:15, Xiangsheng Hou (侯祥胜) wrote:
>>> There have two rx related timing properties in spi-peripheral-
>>> props.
>>> The rx-sample-delay-ns have been used in Mediatek snfi driver to
>>> adjust
>>> controller sample delay.
>>> However another spi-rx-delay-us is in microseconds. Take 52MHz for
>>> example, the clock cycle will be 19.23ns which lower than 1us. This
>>> may
>>> not easy to by one clock cycle.
>> I agree, but nothing prevents you from adding your own property for
>> that.
>> I propose "mediatek,rx-latch-latency-ns" or "mediatek,rx-latency-ns", 
>> so that
>> we can specify the delay in nanoseconds: in that case, when we
>> specify 19ns,
>> the driver will safely round that resulting in 52MHz == 19.23ns =>
>> 19ns valid.
> Will be fixed in next series.

I am fine with this approach, but after explanations I was also fine
with clock cycles as unit. It's still quite specific unit and I think
several timings on buses are clock-cycle dependent, not time dependent.

Best regards,

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