On Wed, Sep 27, 2023 at 11:10:58AM +0200, Geert Uytterhoeven wrote: > On Wed, Sep 27, 2023 at 11:00 AM Mark Brown <broonie@xxxxxxxxxx> wrote: > > The description is clearly saying there is a chip select, _NO_CS seems > > entirely inappropriate. It's not specified in the device tree because > > when there's no chip select for a device it's a fundamental property of > > how the device is controlled and we don't need any information beyond > > the compatible. > In host mode, it indeed doesn't matter, as you can have only a single > device connected with SPI_NO_CS. > In device mode, the device needs to know if it must monitor the chip > select line or not. > In hindsight, I should have kept the question I had written initially, > but deleted after having read the documentation for the corresponding > RZ/V2M register bits: > What does it mean if this is false? That there is no chip select? > So "spi-no-cs" would be the inverse of "renesas,csi-ss". I see. Is there any control over what the chip select is when there is one, in which case we could just look to see if there's one specified? I'm a bit nervous about a generic property that maps onto _NO_CS since it's likely that people will start using that in device bindings when they shouldn't.
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