Re: At86rf212B(driver at86rf230), Ralink MT7228, cs1 always high

[Alexander Aring <alex.aring@gmail.com>]

On Mon, Jun 01, 2015 at 09:00:30AM +0200, Baptiste Clenet wrote:
> Sorry, it was Ralink MT7628.
> I boot via device tree yes and the dts is configured to use AT86RF212B
> with chip select 1 :
> 
> palmbus@10000000 {
>   spi@b00 {
>       status = "okay";
> 
>       m25p80@0 {
>         #address-cells = <1>;
>         #size-cells = <1>;
>         compatible = "en25q64";
>         reg = <0 0>;
>         ...
>       };
> 
>       at86rf212@0 {
>           compatible = "atmel,at86rf212";
>           reg = <1>;

this normally represents the chip select, I don't know if this is just
eye candy or it's _really_ evaluated.

>           interrupts = <15 4>;
>           interrupt-parent = <&intc>;
>           reset-gpio = <&gpio0 16 1>;
>           sleep-gpio = <&gpio0 17 1>;
>           spi-max-frequency = <1000000>;
>       };
>   };
> };
> 
> 
> This didn't work so I had a look a the spi driver spi-mt7621.c and I
> saw that the driver wasn't implemented FOR two chip selects. This is
> why I change the function "static void mt7621_spi_set_cs();" (last
> message)
> 
> Does it make sense?
> 

I think it could make sense, depends what the hardware designer for Ralink
MT7628 did there.

First you need to figure out "who" make your chip select. I mean with
this question, if your SPI controller do the chip select or is it
software triggered by GPIO.

I don't know the spi subsystem much if the lastest one is ever supported
or you need to implement yourself (if possible). I think the spi subsystem
supports that, but I never setup such configuration.

If it's triggered by GPIO (this smells like the spi-mt7621.c function),
you need to care that the cs is handled by software correctly and now I
think that this can have 100 issues why it's not working currently in
your setup.

I think this is more a spi specific question and you should ask on:

http://vger.kernel.org/vger-lists.html#linux-spi

or get commercial support. Sorry, but I can't really help your with a
generic spi question and your issue smells like "reading zeros" on the
bus only.

- Alex