Re: spi-ar934x: Using GPIO CS issue

[Dave Bender <codehero@xxxxxxxxx>]

I've tried different combinations of GPIO_ACTIVE_HIGH/LOW.
I modified the ar9134x-spi.c driver to allow gpiod descriptors.
I've tried creating a virtual CS of 3, using cs-gpios.

Nothing seems to work and all I get are JEDEC IDs of 0's.

Is there something I else I am missing here?
For reference, this is a Carambola 2 module on a custom board, with an
extra SPI 32Mb chip on GPIO11, which is not "HW" chip select pin.

On Thu, Nov 4, 2021 at 11:20 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>
> Hi Dave,
>
> On Thu, Nov 4, 2021 at 3:58 PM Dave Bender <codehero@xxxxxxxxx> wrote:
> > On Thu, Nov 4, 2021 at 5:50 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > > Does it work if you change GPIO_ACTIVE_LOW to GPIO_ACTIVE_HIGH?
> >
> >   There is a pullup resistor on that CS line, so that GPIO must be active low.
>
> I do believe you.  But there's been some issues with inverted CS
> gpio behavior when switching from board files to DT, so I thought
> I'd better ask to try...
>
> >   Digging deeper into the code, it looks like David Bauer made some
> > changes that limit the spi driver's CS usage to only the CS0, CS1, CS2
> > pins.
> >   There is also no bounds checking on the CS value.
> >   I don't understand how this driver can even use generic GPIO if it
> > forces use of the CS bits on the SPI_IOC register.
>
> OK, that sounds like a reasonable culprit...
>
> >
> > static int ar934x_spi_transfer_one_message(struct spi_controller *master,
> >              struct spi_message *m)
> > {
> >    ....
> >    ....
> >     for (trx_done = 0; trx_done < t->len; trx_done += 4) {
> >
> >    .....
> >       reg = AR934X_SPI_SHIFT_VAL(spi->chip_select, term,
> >                trx_cur * 8);
> >       iowrite32(reg, sp->base + AR934X_SPI_REG_SHIFT_CTRL);
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> 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