Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 27 Sep 2023 11:10:58 +0200 | Subject | Re: [PATCH 1/2] spi: renesas,rzv2m-csi: Add SPI Slave related properties |
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Hi Mark,
On Wed, Sep 27, 2023 at 11:00 AM Mark Brown <broonie@kernel.org> wrote: > On Wed, Sep 27, 2023 at 09:59:05AM +0200, Geert Uytterhoeven wrote: > > On Tue, Sep 26, 2023 at 11:08 PM Fabrizio Castro > > > + type: boolean > > > + description: > > > + Use CSI Slave Selection (SS) pin to enable transmission and reception when > > > + in slave mode. > > > Can't this be done in a more generic way? I had expected that the > > existing SPI_NO_CS flag can be set using a property in the "slave" subnode, > > but apparently there is no "spi-no-cs" property defined yet. > > 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".
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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