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Commit d6f1250a authored by Marek Vasut's avatar Marek Vasut Committed by Greg Kroah-Hartman
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i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume



commit 048bbbdbf85e5e00258dfb12f5e368f908801d7b upstream.

In case there is any sort of clock controller attached to this I2C bus
controller, for example Versaclock or even an AIC32x4 I2C codec, then
an I2C transfer triggered from the clock controller clk_ops .prepare
callback may trigger a deadlock on drivers/clk/clk.c prepare_lock mutex.

This is because the clock controller first grabs the prepare_lock mutex
and then performs the prepare operation, including its I2C access. The
I2C access resumes this I2C bus controller via .runtime_resume callback,
which calls clk_prepare_enable(), which attempts to grab the prepare_lock
mutex again and deadlocks.

Since the clock are already prepared since probe() and unprepared in
remove(), use simple clk_enable()/clk_disable() calls to enable and
disable the clock on runtime suspend and resume, to avoid hitting the
prepare_lock mutex.

Acked-by: default avatarAlain Volmat <alain.volmat@foss.st.com>
Signed-off-by: default avatarMarek Vasut <marex@denx.de>
Fixes: 4e7bca6f ("i2c: i2c-stm32f7: add PM Runtime support")
Cc: <stable@vger.kernel.org> # v5.0+
Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f53c1712
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