Re: [PATCH v8 2/2] i2c: designware: defer probe if child GpioInt controllers are not bound

[Nathan Chancellor <nathan@kernel.org>]

Hi Hardik,

On Fri, May 29, 2026 at 03:38:37PM +0530, Hardik Prakash wrote:
> I2C controllers may have child devices with GpioInt resources that
> depend on GPIO controllers to be fully initialized. If the I2C
> controller probes and enumerates children before the referenced GPIO
> controller has completed probe, GPIO interrupts may not be properly
> configured, leading to device failures.
> 
> On Lenovo Yoga 7 14AGP11, the WACF2200 touchscreen (child of
> AMDI0010:02) has a GpioInt resource pointing to GPIO 157 on the
> pinctrl-amd controller (AMDI0030:00). When i2c-designware probes
> AMDI0010:02 before pinctrl-amd finishes initializing, I2C transactions
> occur before the GPIO IRQ quirk in amd_gpio_probe() has run, causing:
> 
>   i2c_designware AMDI0010:02: i2c_dw_handle_tx_abort: lost arbitration
> 
> Add a generic dependency check in i2c-designware that walks ACPI child
> devices, identifies any GpioInt resources, resolves the referenced GPIO
> controllers, and defers probe if those controllers are not yet bound.
> 
> This ensures GPIO controllers complete initialization (including IRQ
> setup and quirks) before I2C child enumeration begins, fixing the race
> without device-specific quirks or DMI matching.
> 
> The probe ordering race was confirmed via dynamic debug tracing:
> 
>   0.285952  amd_gpio_probe: registering gpiochip  <- GPIO chip visible
>   0.287121  amd_gpio_probe: requesting parent IRQ <- probe still running
>   0.301454  AMDI0010:02 dw_i2c_plat_probe: start  <- races here
>   2.348157  lost arbitration
> 
> Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
> Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> Assisted-by: Claude:claude-sonnet-4-6
> Assisted-by: GPT-Codex:gpt-5.2-codex
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202605240959.Kcf1lIg4-lkp@intel.com/
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=221494

I bisected boot issues with a few of my test machines to this change in -next
as commit ef76a3a28c79 ("i2c: designware: defer probe if child GpioInt
controllers are not bound"). I consistently get no display output and I do not
have serial access to these machines, so I do not have much to go on here at
the moment. Occasionally, the network controller will be initialized so I can
remote in but I have not been able to do it recently to try and gather logs.
What information would be useful for trying to figure out what is going on
here? I seem to recall a crash in strcmp() in one log but I cannot be too sure
since it was late at night when I was doing my initial triage.

# bad: [08484c504b55a98bd100527fbe10a3caf55ff3ff] Add linux-next specific files for 20260601
# good: [e43ffb69e0438cddd72aaa30898b4dc446f664f8] Linux 7.1-rc6
git bisect start '08484c504b55a98bd100527fbe10a3caf55ff3ff' 'e43ffb69e0438cddd72aaa30898b4dc446f664f8'
# good: [57fb910db1b6051476b91a4d4ae18bc027a7f36d] Merge branch 'master' of https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
git bisect good 57fb910db1b6051476b91a4d4ae18bc027a7f36d
# good: [18ea7e3ca91e7a9eb9e43c11154350cec160830b] Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/jassibrar/mailbox.git
git bisect good 18ea7e3ca91e7a9eb9e43c11154350cec160830b
# good: [a5696dd9c080352e25b576acf24450cef255b6eb] Merge branch 'tty-next' of https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
git bisect good a5696dd9c080352e25b576acf24450cef255b6eb
# good: [c158564f40f0d2a68833610ac136f9714fc51b16] Merge branch 'staging-next' of https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
git bisect good c158564f40f0d2a68833610ac136f9714fc51b16
# bad: [4240c928a5edeb13fb3953248dfc45e5d9f42f00] Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git
git bisect bad 4240c928a5edeb13fb3953248dfc45e5d9f42f00
# good: [2e24f5964b72ef213ecdb959a0b0d60b2dc00a3b] Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git
git bisect good 2e24f5964b72ef213ecdb959a0b0d60b2dc00a3b
# good: [6a350ccc4dc3f46ed2ee2592e3050956e415ef64] pinctrl: add new generic groups/function creation function for pinmux
git bisect good 6a350ccc4dc3f46ed2ee2592e3050956e415ef64
# good: [b12e12ee4138e30d786eda02223e87044c989bb1] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init
git bisect good b12e12ee4138e30d786eda02223e87044c989bb1
# good: [446fa334d186316e76cbdc4e94e42af7d040a79c] pinctrl: qcom: Replace open coded eoi call with irq_chip_eoi_parent()
git bisect good 446fa334d186316e76cbdc4e94e42af7d040a79c
# good: [a8754838f83a9905af516f38dd2633744a94f71a] gpio: max77620: Unify usage of space and comma in platform_device_id array
git bisect good a8754838f83a9905af516f38dd2633744a94f71a
# bad: [ef76a3a28c79b628890431aa344af633e892035b] i2c: designware: defer probe if child GpioInt controllers are not bound
git bisect bad ef76a3a28c79b628890431aa344af633e892035b
# good: [b0c13ec17438577f90b379d448dfed1233e2c0a4] pinctrl: mcp23s08: Read spi-present-mask as u8 not u32
git bisect good b0c13ec17438577f90b379d448dfed1233e2c0a4
# good: [3f786abd23951f3f600a62fef42469d9200d5f52] Revert "pinctrl-amd: enable IRQ for WACF2200 touchscreen on Lenovo Yoga 7 14AGP11"
git bisect good 3f786abd23951f3f600a62fef42469d9200d5f52
# first bad commit: [ef76a3a28c79b628890431aa344af633e892035b] i2c: designware: defer probe if child GpioInt controllers are not bound

-- 
Cheers,
Nathan