From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bitan Biswas Subject: Re: [PATCH V2] i2c: busses: tegra: Add suspend-resume support Date: Thu, 6 Jun 2019 06:58:53 -0700 Message-ID: <5871f51b-11d4-8bc9-6f40-4a91f2aab8f8@nvidia.com> References: <1559800475-5446-1-git-send-email-bbiswas@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , Laxman Dewangan , Thierry Reding , Jonathan Hunter , linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Shardar Mohammed , Sowjanya Komatineni , Mantravadi Karthik List-Id: linux-i2c@vger.kernel.org On 6/6/19 5:06 AM, Dmitry Osipenko wrote: > 06.06.2019 8:54, Bitan Biswas =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> Post suspend I2C registers have power on reset values. Before any >> transfer initialize I2C registers to prevent I2C transfer timeout >> and implement suspend and resume callbacks needed. Fix below errors >> post suspend: >> >> 1) Tegra I2C transfer timeout during jetson tx2 resume: >> >> [ 27.520613] pca953x 1-0074: calling pca953x_resume+0x0/0x1b0 @ 2939, = parent: i2c-1 >> [ 27.633623] tegra-i2c 3160000.i2c: i2c transfer timed out >> [ 27.639162] pca953x 1-0074: Unable to sync registers 0x3-0x5. -110 >> [ 27.645336] pca953x 1-0074: Failed to sync GPIO dir registers: -110 >> [ 27.651596] PM: dpm_run_callback(): pca953x_resume+0x0/0x1b0 returns = -110 >> [ 27.658375] pca953x 1-0074: pca953x_resume+0x0/0x1b0 returned -110 af= ter 127152 usecs >> [ 27.666194] PM: Device 1-0074 failed to resume: error -110 >> >> 2) Tegra I2C transfer timeout error on jetson Xavier post resume. >> >> Remove i2c bus lock-unlock calls in resume callback as i2c_mark_adapter_= * >> (suspended-resumed) help ensure i2c core calls from client are not >> executed before i2c-tegra resume. >> >> Signed-off-by: Bitan Biswas >> --- >> drivers/i2c/busses/i2c-tegra.c | 23 +++++++++++++++++++++++ >> 1 file changed, 23 insertions(+) >> >> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-teg= ra.c >> index ebaa78d..76b7926 100644 >> --- a/drivers/i2c/busses/i2c-tegra.c >> +++ b/drivers/i2c/busses/i2c-tegra.c >> @@ -1687,7 +1687,30 @@ static int tegra_i2c_remove(struct platform_devic= e *pdev) >> } >> =20 >> #ifdef CONFIG_PM_SLEEP >> +static int tegra_i2c_suspend(struct device *dev) >> +{ >> + struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(dev); >> + >> + i2c_mark_adapter_suspended(&i2c_dev->adapter); >> + >> + return 0; >> +} >> + >> +static int tegra_i2c_resume(struct device *dev) >> +{ >> + struct tegra_i2c_dev *i2c_dev =3D dev_get_drvdata(dev); >> + int ret; >> + >> + ret =3D tegra_i2c_init(i2c_dev, false); >> + if (ret) >> + return ret; >=20 > We're expecting that tegra_i2c_init returns a error code on a failure > and nothing else, hence it will be a bit more expressive to name the > returned variable as "err". There is nothing wrong with yours variant, > this is just a very minor recommendation from me. Please note that a bit > more wise choice of the names makes easier to follow the code for other > people and hence results in a cleaner code. Agreed. >=20 >> + >> + i2c_mark_adapter_resumed(&i2c_dev->adapter); >=20 > Please add a blank line here for a better readability and to make the > patch consistent. You added the blank line in a similar case of > tegra_i2c_suspend() and this makes it inconsistent. >=20 OK. >> + return 0; >> +} >> + >> static const struct dev_pm_ops tegra_i2c_pm =3D { >> + SET_SYSTEM_SLEEP_PM_OPS(tegra_i2c_suspend, tegra_i2c_resume) >> SET_RUNTIME_PM_OPS(tegra_i2c_runtime_suspend, tegra_i2c_runtime_resum= e, >> NULL) >> }; >> I shall send updated patch with suggested changes. -thanks, Bitan