From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH 2/5] i2c: tegra: Restore pinmux on system resume Date: Fri, 8 May 2020 00:50:09 +0300 Message-ID: <2a0404ac-73bf-2f27-9147-8bef28ae995f@gmail.com> References: <20200506193358.2807244-1-thierry.reding@gmail.com> <20200506193358.2807244-3-thierry.reding@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200506193358.2807244-3-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding , Wolfram Sang Cc: Jon Hunter , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org 06.05.2020 22:33, Thierry Reding пишет: > From: Thierry Reding > > 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 > --- > 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?