Hi Angelo, On Tue, 2022-12-06 at 13:19 +0100, AngeloGioacchino Del Regno wrote: > > > > diff --git > > > > a/Documentation/devicetree/bindings/spi/mediatek,spi- > > > > mtk-snfi.yaml > > > > b/Documentation/devicetree/bindings/spi/mediatek,spi- > > > > mtk-snfi.yaml > > > > index bab23f1b11fd..6e6ff8d73fcd 100644 > > > > --- a/Documentation/devicetree/bindings/spi/mediatek,spi-mtk- > > > > snfi.yaml > > > > +++ b/Documentation/devicetree/bindings/spi/mediatek,spi-mtk- > > > > snfi.yaml > > > > @@ -45,6 +45,13 @@ properties: > > > > description: device-tree node of the accompanying ECC > > > > engine. > > > > $ref: /schemas/types.yaml#/definitions/phandle > > > > > > > > + mediatek,rx-latch-latency: > > > > + description: Rx delay to sample data with this value, the > > > > value > > > > + unit is clock cycle. > > > > > > Can't we use nanoseconds or microseconds as a unit here, instead > > > of > > > clock cycles? > > > > The clock cycle will be various with MediaTek SPI NAND controller > > which > > clock frequency can support 26/52/68/81/104MHz... > > It`s may be easy to configure and understand with clock cycle in > > unit. > > > > Yes, but whatever clock frequency we use, the target is to always > wait for > X nanoseconds, right? > > Waiting for 5 clock cycles at 104MHz is obviously not the same as > waiting > for the same 5 clock cycles at 26MHz: in that case, expressing the > value > in nanoseconds or microseconds would make that independent from the > controller's clock frequency as the calculation from `time` to > `cycles` > would be performed inside of the driver. 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. Thanks Xiangsheng Hou
