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SubjectRe: [PATCH] pinctrl: initialise nsp-mux earlier.
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On 6/30/2020 9:37 PM, Mark Tomlinson wrote:
> 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/

clk or reset APIs do not complain loudly on EPROBE_DEFER, it seems to me
that GPIO should follow here. Also, it does look like Linus was in
agreement in the end, not sure why it was not applied though.
--
Florian

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