06.05.2020 22:33, Thierry Reding пишет: > From: Thierry Reding <treding@xxxxxxxxxx> > > Depending on the board design, the I2C controllers found on Tegra SoCs > may require pinmuxing in order to function. This is done as part of the > driver's runtime suspend/resume operations. However, the PM core does > not allow devices to go into runtime suspend during system sleep to > avoid potential races with the suspend/resume of their parents. > > As a result of this, when Tegra SoCs resume from system suspend, their > I2C controllers may have lost the pinmux state in hardware, whereas the > pinctrl subsystem is not aware of this. To fix this, make sure that if > the I2C controller is not runtime suspended, the runtime suspend code is > still executed in order to disable the module clock (which we don't need > to be enabled during sleep) and set the pinmux to the idle state. > > Conversely, make sure that the I2C controller is properly resumed when > waking up from sleep so that pinmux settings are properly restored. > > This fixes a bug seen with DDC transactions to an HDMI monitor timing > out when resuming from system suspend. > > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> > --- > drivers/i2c/busses/i2c-tegra.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c > index 7c88611c732c..db142d897604 100644 > --- a/drivers/i2c/busses/i2c-tegra.c > +++ b/drivers/i2c/busses/i2c-tegra.c > @@ -1769,10 +1769,14 @@ static int tegra_i2c_remove(struct platform_device *pdev) > static int __maybe_unused tegra_i2c_suspend(struct device *dev) > { > struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev); > + int err = 0; > > i2c_mark_adapter_suspended(&i2c_dev->adapter); > > - return 0; > + if (!pm_runtime_status_suspended(dev)) > + err = tegra_i2c_runtime_suspend(dev); > + > + return err; > } > > static int __maybe_unused tegra_i2c_resume(struct device *dev) > @@ -1788,9 +1792,11 @@ static int __maybe_unused tegra_i2c_resume(struct device *dev) > if (err) > return err; > > - err = tegra_i2c_runtime_suspend(dev); > - if (err) > - return err; > + if (pm_runtime_status_suspended(dev)) { > + err = tegra_i2c_runtime_suspend(dev); > + if (err) > + return err; > + } > > i2c_mark_adapter_resumed(&i2c_dev->adapter); > > Is it legal to touch DPAUX registers while DPAUX is in a suspended state?