Message ID | 20240930192820.59719-1-marex@denx.de (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | [v2] i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume | expand |
On Mon, Sep 30, 2024 at 09:27:41PM GMT, Marek Vasut wrote: > 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> I think we also need: Fixes: 4e7bca6fc07b ("i2c: i2c-stm32f7: add PM Runtime support") Cc: <stable@vger.kernel.org> # v5.0+ I'm adding them, please, let me know if you think they are not needed. For now I merged this patch in i2c/i2c-host-fixes. Thanks, Andi
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c index cfee2d9c09de3..0174ead99de6c 100644 --- a/drivers/i2c/busses/i2c-stm32f7.c +++ b/drivers/i2c/busses/i2c-stm32f7.c @@ -2395,7 +2395,7 @@ static int __maybe_unused stm32f7_i2c_runtime_suspend(struct device *dev) 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; } @@ -2406,9 +2406,9 @@ static int __maybe_unused stm32f7_i2c_runtime_resume(struct device *dev) 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; } }