| Message ID | 20211014110437.64764-1-shreeya.patel@collabora.com |
|---|---|
| State | New |
| Headers | show |
| Series | gpio: Return EPROBE_DEFER if gc->to_irq is NULL | expand |
On Thu, Oct 14, 2021 at 1:05 PM Shreeya Patel <shreeya.patel@collabora.com> 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 <shreeya.patel@collabora.com> 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 > <shreeya.patel@collabora.com> 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 <shreeya.patel@collabora.com> > 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
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);
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 <shreeya.patel@collabora.com> --- drivers/gpio/gpiolib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)