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* [PATCH] pinctrl: initialise nsp-mux earlier.
@ 2020-06-30 21:29 Mark Tomlinson
  2020-06-30 22:08 ` Ray Jui
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Tomlinson @ 2020-06-30 21:29 UTC (permalink / raw)
  To: rjui, sbranden, bcm-kernel-feedback-list, linus.walleij, linux-gpio
  Cc: linux-kernel, Mark Tomlinson

The GPIO specified in the DTS file references the pinctrl, which is
specified after the GPIO. If the GPIO is initialised before pinctrl,
an error message for the -EPROBE_DEFER ends up in the kernel log. Even
though the probe will succeed when the driver is re-initialised, the
error can be scary to end users. To fix this, change the time the
pinctrl is probed, so that it is always before the GPIO driver.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
---
 drivers/pinctrl/bcm/pinctrl-nsp-mux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-mux.c b/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
index f1d60a708815..7586949f83ec 100644
--- a/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
+++ b/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
@@ -639,4 +639,4 @@ static int __init nsp_pinmux_init(void)
 {
 	return platform_driver_register(&nsp_pinmux_driver);
 }
-arch_initcall(nsp_pinmux_init);
+postcore_initcall(nsp_pinmux_init);
-- 
2.27.0


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] pinctrl: initialise nsp-mux earlier.
  2020-06-30 21:29 [PATCH] pinctrl: initialise nsp-mux earlier Mark Tomlinson
@ 2020-06-30 22:08 ` Ray Jui
  2020-07-01  2:23   ` Mark Tomlinson
  0 siblings, 1 reply; 6+ messages in thread
From: Ray Jui @ 2020-06-30 22:08 UTC (permalink / raw)
  To: Mark Tomlinson, rjui, sbranden, bcm-kernel-feedback-list,
	linus.walleij, linux-gpio
  Cc: linux-kernel

Hi Mark,

On 6/30/2020 2:29 PM, Mark Tomlinson wrote:
> The GPIO specified in the DTS file references the pinctrl, which is
> specified after the GPIO. If the GPIO is initialised before pinctrl,

May I know which GPIO driver you are referring to on NSP? Both the iProc
GPIO driver and the NSP GPIO driver are initialized at the level of
'arch_initcall_sync', which is supposed to be after 'arch_initcall' used
here in the pinmux driver

> an error message for the -EPROBE_DEFER ends up in the kernel log. Even
> though the probe will succeed when the driver is re-initialised, the
> error can be scary to end users. To fix this, change the time the

Scary to end users? I don't know about that. -EPROBE_DEFER was
introduced exactly for this purpose. Perhaps users need to learn what
-EPROBE_DEFER errno means?

> pinctrl is probed, so that it is always before the GPIO driver.
> 
> Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
> ---
>  drivers/pinctrl/bcm/pinctrl-nsp-mux.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/bcm/pinctrl-nsp-mux.c b/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
> index f1d60a708815..7586949f83ec 100644
> --- a/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
> +++ b/drivers/pinctrl/bcm/pinctrl-nsp-mux.c
> @@ -639,4 +639,4 @@ static int __init nsp_pinmux_init(void)
>  {
>  	return platform_driver_register(&nsp_pinmux_driver);
>  }
> -arch_initcall(nsp_pinmux_init);
> +postcore_initcall(nsp_pinmux_init);
> 

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] pinctrl: initialise nsp-mux earlier.
  2020-06-30 22:08 ` Ray Jui
@ 2020-07-01  2:23   ` Mark Tomlinson
  2020-07-01  3:14     ` Florian Fainelli
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Tomlinson @ 2020-07-01  2:23 UTC (permalink / raw)
  To: ray.jui, bcm-kernel-feedback-list, linus.walleij, linux-gpio,
	sbranden, rjui
  Cc: linux-kernel

On Tue, 2020-06-30 at 15:08 -0700, Ray Jui wrote:
> May I know which GPIO driver you are referring to on NSP? Both the iProc
> GPIO driver and the NSP GPIO driver are initialized at the level of
> 'arch_initcall_sync', which is supposed to be after 'arch_initcall' used
> here in the pinmux driver

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?

> > though the probe will succeed when the driver is re-initialised, the
> > error can be scary to end users. To fix this, change the time the
> 
> Scary to end users? I don't know about that. -EPROBE_DEFER was
> introduced exactly for this purpose. Perhaps users need to learn what
> -EPROBE_DEFER errno means?

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.


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] pinctrl: initialise nsp-mux earlier.
  2020-07-01  2:23   ` Mark Tomlinson
@ 2020-07-01  3:14     ` Florian Fainelli
  2020-07-01  4:37       ` Mark Tomlinson
  0 siblings, 1 reply; 6+ messages in thread
From: Florian Fainelli @ 2020-07-01  3:14 UTC (permalink / raw)
  To: Mark Tomlinson, ray.jui, bcm-kernel-feedback-list, linus.walleij,
	linux-gpio, sbranden, rjui
  Cc: linux-kernel



On 6/30/2020 7:23 PM, Mark Tomlinson wrote:
> On Tue, 2020-06-30 at 15:08 -0700, Ray Jui wrote:
>> May I know which GPIO driver you are referring to on NSP? Both the iProc
>> GPIO driver and the NSP GPIO driver are initialized at the level of
>> 'arch_initcall_sync', which is supposed to be after 'arch_initcall' used
>> here in the pinmux driver
> 
> 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?

> 
>>> though the probe will succeed when the driver is re-initialised, the
>>> error can be scary to end users. To fix this, change the time the
>>
>> Scary to end users? I don't know about that. -EPROBE_DEFER was
>> introduced exactly for this purpose. Perhaps users need to learn what
>> -EPROBE_DEFER errno means?
> 
> 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;
 }

-- 
Florian

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] pinctrl: initialise nsp-mux earlier.
  2020-07-01  3:14     ` Florian Fainelli
@ 2020-07-01  4:37       ` Mark Tomlinson
  2020-07-01  4:44         ` Florian Fainelli
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Tomlinson @ 2020-07-01  4:37 UTC (permalink / raw)
  To: ray.jui, bcm-kernel-feedback-list, f.fainelli, linux-gpio,
	linus.walleij, sbranden, rjui
  Cc: linux-kernel

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/


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] pinctrl: initialise nsp-mux earlier.
  2020-07-01  4:37       ` Mark Tomlinson
@ 2020-07-01  4:44         ` Florian Fainelli
  0 siblings, 0 replies; 6+ messages in thread
From: Florian Fainelli @ 2020-07-01  4:44 UTC (permalink / raw)
  To: Mark Tomlinson, ray.jui, bcm-kernel-feedback-list, linux-gpio,
	linus.walleij, sbranden, rjui
  Cc: linux-kernel



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

^ permalink raw reply	[flat|nested] 6+ messages in thread

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Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-30 21:29 [PATCH] pinctrl: initialise nsp-mux earlier Mark Tomlinson
2020-06-30 22:08 ` Ray Jui
2020-07-01  2:23   ` Mark Tomlinson
2020-07-01  3:14     ` Florian Fainelli
2020-07-01  4:37       ` Mark Tomlinson
2020-07-01  4:44         ` Florian Fainelli

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