Re: Boot failure with 5.4-rc5, bisected to 0f0581b24bd0 ("spi: fsl: Convert to use CS GPIO descriptors")

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Wed, Nov 27, 2019 at 11:39 AM Christophe Leroy
<christophe.leroy@xxxxxx> wrote:
> Le 27/11/2019 à 11:02, Linus Walleij a écrit :
> > On Wed, Nov 27, 2019 at 10:34 AM Christophe Leroy
> > <christophe.leroy@xxxxxx> wrote:
> >
> >> In the meantime, I have tried changing "gpios" by "cs-gpios" in the
> >> device tree, and I get the following warning:
> > (...)
> >> [    3.156654] WARNING: CPU: 0 PID: 1 at drivers/spi/spi-fsl-spi.c:716
> >> fsl_spi_cs_control+0x64/0x7c
> >
> > That should be this one:
> >
> > if (WARN_ON_ONCE(!pinfo->immr_spi_cs))
> >     return;
> >
> > That happens when spi->cs_gpiod is NULL so the
> > chipselect isn't found and assigned, and the code
> > goes on to check the native CS and find that this isn't
> > available either and issues the warning.
>
> That's in spi_add_device(), it is spi->cs_gpio and not spi->cs_gpiod
> which is assigned, so spi->cs_gpiod remains NULL.

That's weird, because when ->use_gpio_descriptors is set
(as for this driver) the core only attempts to look up
spi->cs_gpiods and not spi->cs_gpios, and consequently
can only assign spi->cd_gpiod and not spi->cs_gpio:

if (ctlr->use_gpio_descriptors) {
    status = spi_get_gpio_descs(ctlr);
(...)
} else {
(....)
    status = of_spi_get_gpio_numbers(ctlr);
}
(...)
/* Descriptors take precedence */
if (ctlr->cs_gpiods)
    spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
else if (ctlr->cs_gpios)
    spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];

So I'm a bit confused...

Yours,
Linus Walleij