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Subject: async probe: boot crash with v5.10.188 on STM32MP157
From:   Antonio Borneo <antonio.borneo@foss.st.com>
To:     Saravana Kannan <saravanak@google.com>
CC:     Linus Walleij <linus.walleij@linaro.org>,
        <linux-kernel@vger.kernel.org>,
        Alexandre TORGUE <alexandre.torgue@foss.st.com>
Date:   Mon, 18 Sep 2023 14:26:21 +0200
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Hi Saravana,

while devlink and async probe looks ok in v6.6-rc1, I get randomly boot
crash on STM32MP157 with kernel v5.10.188 after the upstream commit
3108eb2e8aa7 ("mmc: mmci: Set PROBE_PREFER_ASYNCHRONOUS") got backported.

In v6.6-rc1, really_probe() checks for probe dependencies with
device_links_check_suppliers(). In older kernels this part is missing.
In the specific case of STM32MP157, the driver mmci can get async-probed
while the probe of pinctrl/stm32/pinctrl-stm32.c has already registered
the pinctrl but has not added any gpiochip yet.
This causes pinmux_ops::set_mux() to fail and thus mmci probe fails too.

Boot log contains:

[2.205476] stm32mp157-pinctrl soc:pin-controller@50002000: No gpio range de=
fined.
[2.205515] mmci-pl18x 58005000.sdmmc: Error applying setting, reverse thing=
s back
[2.205828] mmci-pl18x: probe of 58005000.sdmmc failed with error -22
[2.210434] stm32mp157-pinctrl soc:pin-controller@50002000: GPIOA bank added

From a quick code check, also the LTS v5.15 and v6.1 looks impacted, but
I have not tested them, so far, due to the difficulties to replicate the
crash.

Is there any mandatory upstream patch that got lost in the backport process=
?

Or is there something incorrect to be fixed in pinctrl-stm32 driver?

What are the possible workaround I can use? Would kernel flag fw_devlink=3D=
off
work reliably for all the mentioned kernel versions?

Regards,
Antonio