We are racing the registering of .to_irq when probing the
i2c driver. This results in random failure of touchscreen
devices.
Following errors could be seen in dmesg logs when gc->to_irq is NULL
[2.101857] i2c_hid i2c-FTS3528:00: HID over i2c has not been provided an Int IRQ
[2.101953] i2c_hid: probe of i2c-FTS3528:00 failed with error -22
To avoid this situation, defer probing until to_irq is registered.
This issue has been reported many times in past and people have been
using workarounds like changing the pinctrl_amd to built-in instead
of loading it as a module or by adding a softdep for pinctrl_amd into
the config file.
References :-
https://bugzilla.kernel.org/show_bug.cgi?id=209413
https://github.com/Syniurge/i2c-amd-mp2/issues/3
Signed-off-by: Shreeya Patel <[email protected]>
---
drivers/gpio/gpiolib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 27c07108496d..fc0ba85f4c45 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3084,7 +3084,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
return retirq;
}
- return -ENXIO;
+ return -EPROBE_DEFER;
}
EXPORT_SYMBOL_GPL(gpiod_to_irq);
--
2.30.2
On Thu, Oct 14, 2021 at 1:05 PM Shreeya Patel
<[email protected]> wrote:
> We are racing the registering of .to_irq when probing the
> i2c driver. This results in random failure of touchscreen
> devices.
>
> Following errors could be seen in dmesg logs when gc->to_irq is NULL
>
> [2.101857] i2c_hid i2c-FTS3528:00: HID over i2c has not been provided an Int IRQ
> [2.101953] i2c_hid: probe of i2c-FTS3528:00 failed with error -22
>
> To avoid this situation, defer probing until to_irq is registered.
>
> This issue has been reported many times in past and people have been
> using workarounds like changing the pinctrl_amd to built-in instead
> of loading it as a module or by adding a softdep for pinctrl_amd into
> the config file.
>
> References :-
> https://bugzilla.kernel.org/show_bug.cgi?id=209413
> https://github.com/Syniurge/i2c-amd-mp2/issues/3
>
> Signed-off-by: Shreeya Patel <[email protected]>
I understand the issue.
There is one problem.
> @@ -3084,7 +3084,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
>
> return retirq;
> }
> - return -ENXIO;
> + return -EPROBE_DEFER;
If you after five minutes plug in a USB FTDI or similar UART thing
with a GPIO expander, and someone request an IRQ from
one of those lines (they do not support interrupts), why should
it return -EPROBE_DEFER?
The point is that I think this will in certain circumstances return
a bogus error.
We cannot merge this other than with a fat comment above:
/*
* This is semantically WRONG because the -EPROBE_DEFER
* is really just applicable during system bring-up.
*/
return -EPROBE_DEFER;
Can we use some kind of late_initcall() to just switch this over
to -ENXIO after a while?
Yours,
Linus Walleij
On 14/10/21 10:21 pm, Linus Walleij wrote:
> On Thu, Oct 14, 2021 at 1:05 PM Shreeya Patel
> <[email protected]> wrote:
>
>> We are racing the registering of .to_irq when probing the
>> i2c driver. This results in random failure of touchscreen
>> devices.
>>
>> Following errors could be seen in dmesg logs when gc->to_irq is NULL
>>
>> [2.101857] i2c_hid i2c-FTS3528:00: HID over i2c has not been provided an Int IRQ
>> [2.101953] i2c_hid: probe of i2c-FTS3528:00 failed with error -22
>>
>> To avoid this situation, defer probing until to_irq is registered.
>>
>> This issue has been reported many times in past and people have been
>> using workarounds like changing the pinctrl_amd to built-in instead
>> of loading it as a module or by adding a softdep for pinctrl_amd into
>> the config file.
>>
>> References :-
>> https://bugzilla.kernel.org/show_bug.cgi?id=209413
>> https://github.com/Syniurge/i2c-amd-mp2/issues/3
>>
>> Signed-off-by: Shreeya Patel <[email protected]>
> I understand the issue.
>
> There is one problem.
>
>> @@ -3084,7 +3084,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
>>
>> return retirq;
>> }
>> - return -ENXIO;
>> + return -EPROBE_DEFER;
> If you after five minutes plug in a USB FTDI or similar UART thing
> with a GPIO expander, and someone request an IRQ from
> one of those lines (they do not support interrupts), why should
> it return -EPROBE_DEFER?
>
> The point is that I think this will in certain circumstances return
> a bogus error.
I was worried about the same but didn't really know under what scenario
this could occur.
Thanks for pointing this out.
>
> We cannot merge this other than with a fat comment above:
>
> /*
> * This is semantically WRONG because the -EPROBE_DEFER
> * is really just applicable during system bring-up.
> */
> return -EPROBE_DEFER;
>
> Can we use some kind of late_initcall() to just switch this over
> to -ENXIO after a while?
I have sent a v2 which tries to fix this in an easy way. Let me know
what do you
think about that approach or else we could also think about using
late_initcall().
Thanks,
Shreeya Patel
> Yours,
> Linus Walleij