Re: [PATCH] pinctrl: initialise nsp-mux earlier.

[Mark Tomlinson <Mark.Tomlinson@alliedtelesis.co.nz>]

On Tue, 2020-06-30 at 20:14 -0700, Florian Fainelli wrote:
> Sorry, it looks like I made a mistake in my testing (or I was lucky),
> > and this patch doesn't fix the issue. What is happening is:
> > 1) nsp-pinmux driver is registered (arch_initcall).
> > 2) nsp-gpio-a driver is registered (arch_initcall_sync).
> > 3) of_platform_default_populate_init() is called (also at level
> > arch_initcall_sync), which scans the device tree, adds the nsp-gpio-a
> > device, runs its probe, and this returns -EPROBE_DEFER with the error
> > message.
> > 4) Only now nsp-pinmux device is probed.
> > 
> > Changing the 'arch_initcall_sync' to 'device_initcall' in nsp-gpio-a
> > ensures that the pinmux is probed first since
> > of_platform_default_populate_init() will be called between the two
> > register calls, and the error goes away. Is this change acceptable as a
> > solution?
> 
> If probe deferral did not work, certainly but it sounds like this is
> being done just for the sake of eliminating a round of probe deferral,
> is there a functional problem this is fixing?

No, I'm just trying to prevent an "error" message appearing in syslog.

> > The actual error message in syslog is:
> > 
> > kern.err kernel: gpiochip_add_data_with_key: GPIOs 480..511
> > (18000020.gpio) failed to register, -517
> > 
> > So an end user sees "err" and "failed", and doesn't know what "-517"
> > means.
> 
> How about this instead:
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 4fa075d49fbc..10d9d0c17c9e 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1818,9 +1818,10 @@ int gpiochip_add_data_with_key(struct gpio_chip
> *gc, void *data,
>         ida_simple_remove(&gpio_ida, gdev->id);
>  err_free_gdev:
>         /* failures here can mean systems won't boot... */
> -       pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__,
> -              gdev->base, gdev->base + gdev->ngpio - 1,
> -              gc->label ? : "generic", ret);
> +       if (ret != -EPROBE_DEFER)
> +               pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n",
> +                       __func__, gdev->base, gdev->base + gdev->ngpio - 1,
> +                       gc->label ? : "generic", ret);
>         kfree(gdev);
>         return ret;
>  }
> 
That was one of my thoughts too. I found someone had tried that
earlier, but it was rejected:


https://patchwork.ozlabs.org/project/linux-gpio/patch/1516566774-1786-1-git-send-email-david@lechnology.com/