Messages in this thread | | | Date | Tue, 21 Jun 2022 12:32:31 +0300 | From | Serge Semin <> | Subject | Re: [PATCH 06/14] spi: dt-bindings: dw-apb-ssi: update spi-{r,t}x-bus-width for dwc-ssi |
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Hi Geert
On Tue, Jun 21, 2022 at 09:03:25AM +0200, Geert Uytterhoeven wrote: > Hi Serge, > > On Mon, Jun 20, 2022 at 10:56 PM Serge Semin <fancer.lancer@gmail.com> wrote: > > On Sat, Jun 18, 2022 at 01:30:28PM +0100, Conor Dooley wrote: > > > From: Conor Dooley <conor.dooley@microchip.com> > > >
[...]
> > > + > > > + spi-rx-bus-width: > > > + const: 1 > > > + > > > + spi-tx-bus-width: > > > + const: 1 > > > > You can just use a more relaxed constraint "enum: [1 2 4 8]" here > > irrespective from the compatible string. The modern DW APB SSI > > controllers of v.4.* and newer also support the enhanced SPI Modes too > > (Dual, Quad and Octal). Since the IP-core version is auto-detected at > > run-time there is no way to create a DT-schema correctly constraining > > the Rx/Tx SPI bus widths. So let's keep the > > compatible-string-independent "patternProperties" here but just extend > > the set of acceptable "spi-rx-bus-width" and "spi-tx-bus-width" > > properties values. > >
> > Note the DW APB SSI/AHB SSI driver currently doesn't support the > > enhanced SPI modes. So I am not sure whether the multi-lines Rx/Tx SPI > > bus indeed works for Canaan K210 AHB SSI controller. AFAICS from the > > DW APB SSI v4.01a manual the Enhanced SPI mode needs to be properly > > activated by means of the corresponding CSR. So most likely the DW AHB > > SSI controllers need some specific setups too. > > That doesn't matter here, as DT describes hardware, not software > limitations.
Can't argue with that.) My note regarding the current DW APB SSI driver was mainly addressed for the Canaan K210 users, since should the SoC-based board really have the Quad Tx/Rx SPI bus most likely the interface won't work with the full bandwidth. So it is a good reason to perform the platform research and if possible alter the driver accordingly.
-Sergey
> > 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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