linux-kernel - Re: [PATCH v4] gpio: Return EPROBE_DEFER if gc->to

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Date:   Thu, 10 Feb 2022 11:36:54 -0500
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     Shreeya Patel <shreeya.patel@...labora.com>, brgl@...ev.pl
Cc:     linus.walleij@...aro.org, andy.shevchenko@...il.com,
        bgolaszewski@...libre.com, wsa@...nel.org, kernel@...labora.com,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, lkp@...el.com
Subject: Re: [PATCH v4] gpio: Return EPROBE_DEFER if gc->to_irq is NULL

Shreeya Patel <shreeya.patel@...labora.com> writes:

> 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.
>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209413
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>

Hi guys,

This seems to not have reached the Linus tree on 5.17.  If I'm not
mistaken, it also hasn't reached linux-next as of today. Is there
anything I'm missing here?

This is required to prevent spurious probe crashes of devices like this
FocalTech touchscreen, FT3528, when using pinctrl-amd. We've been
carrying it downstream for quite a while.

Thanks,

-- 
Gabriel Krisman Bertazi