On Thu, Oct 14, 2021 at 1:05 PM Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> 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
