5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marek Vasut marex@denx.de
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: Alain Volmat alain.volmat@foss.st.com Signed-off-by: Marek Vasut marex@denx.de Fixes: 4e7bca6fc07b ("i2c: i2c-stm32f7: add PM Runtime support") Cc: stable@vger.kernel.org # v5.0+ Signed-off-by: Andi Shyti andi.shyti@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i2c/busses/i2c-stm32f7.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/i2c/busses/i2c-stm32f7.c +++ b/drivers/i2c/busses/i2c-stm32f7.c @@ -2070,7 +2070,7 @@ static int stm32f7_i2c_runtime_suspend(s struct stm32f7_i2c_dev *i2c_dev = dev_get_drvdata(dev);
if (!stm32f7_i2c_is_slave_registered(i2c_dev)) - clk_disable_unprepare(i2c_dev->clk); + clk_disable(i2c_dev->clk);
return 0; } @@ -2081,9 +2081,9 @@ static int stm32f7_i2c_runtime_resume(st int ret;
if (!stm32f7_i2c_is_slave_registered(i2c_dev)) { - ret = clk_prepare_enable(i2c_dev->clk); + ret = clk_enable(i2c_dev->clk); if (ret) { - dev_err(dev, "failed to prepare_enable clock\n"); + dev_err(dev, "failed to enable clock\n"); return ret; } }