[PATCH] driver: pca953x: avoid error message when resuming

[PATCH] driver: pca953x: avoid error message when resuming

[Alifer Moraes]

From: FrancescoFerraro <francesco.f@variscite.com>

Avoids the error messages "pca953x 1-0020: failed reading register"
when resuming from suspend using gpio-key attached to pca9534.

Signed-off-by: Francesco Ferraro <francesco.f@variscite.com>
Signed-off-by: Alifer Moraes <alifer.m@variscite.com>
---
 drivers/gpio/gpio-pca953x.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index d2fe76f3f34f..4f35b75dcbb1 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -211,6 +211,7 @@ struct pca953x_chip {
 	struct regulator *regulator;
 
 	const struct pca953x_reg_config *regs;
+	int is_in_suspend;
 };
 
 static int pca953x_bank_shift(struct pca953x_chip *chip)
@@ -412,7 +413,8 @@ static int pca953x_read_regs(struct pca953x_chip *chip, int reg, unsigned long *
 
 	ret = regmap_bulk_read(chip->regmap, regaddr, value, NBANK(chip));
 	if (ret < 0) {
-		dev_err(&chip->client->dev, "failed reading register\n");
+		if (!chip->is_in_suspend)
+			dev_err(&chip->client->dev, "failed reading register\n");
 		return ret;
 	}
 
@@ -954,6 +956,7 @@ static int pca953x_probe(struct i2c_client *client,
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (chip == NULL)
 		return -ENOMEM;
+	chip->is_in_suspend = 0;
 
 	pdata = dev_get_platdata(&client->dev);
 	if (pdata) {
@@ -1161,6 +1164,8 @@ static int pca953x_suspend(struct device *dev)
 	else
 		regulator_disable(chip->regulator);
 
+	chip->is_in_suspend = 1;
+
 	return 0;
 }
 
@@ -1189,6 +1194,8 @@ static int pca953x_resume(struct device *dev)
 		return ret;
 	}
 
+	chip->is_in_suspend = 0;
+
 	return 0;
 }
 #endif
-- 
2.25.1

Re: [PATCH] driver: pca953x: avoid error message when resuming

[Bartosz Golaszewski]

On Mon, Mar 7, 2022 at 3:20 PM Alifer Moraes <alifer.m@variscite.com> wrote:
>
> From: FrancescoFerraro <francesco.f@variscite.com>
>
> Avoids the error messages "pca953x 1-0020: failed reading register"
> when resuming from suspend using gpio-key attached to pca9534.
>

The commit message should read: "gpio: pca953x: ..."

> Signed-off-by: Francesco Ferraro <francesco.f@variscite.com>
> Signed-off-by: Alifer Moraes <alifer.m@variscite.com>
> ---
>  drivers/gpio/gpio-pca953x.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> index d2fe76f3f34f..4f35b75dcbb1 100644
> --- a/drivers/gpio/gpio-pca953x.c
> +++ b/drivers/gpio/gpio-pca953x.c
> @@ -211,6 +211,7 @@ struct pca953x_chip {
>         struct regulator *regulator;
>
>         const struct pca953x_reg_config *regs;
> +       int is_in_suspend;

Something like this is not needed because we already have
pm_runtime_status_suspended().

>  };
>
>  static int pca953x_bank_shift(struct pca953x_chip *chip)
> @@ -412,7 +413,8 @@ static int pca953x_read_regs(struct pca953x_chip *chip, int reg, unsigned long *
>
>         ret = regmap_bulk_read(chip->regmap, regaddr, value, NBANK(chip));
>         if (ret < 0) {
> -               dev_err(&chip->client->dev, "failed reading register\n");
> +               if (!chip->is_in_suspend)
> +                       dev_err(&chip->client->dev, "failed reading register\n");
>                 return ret;
>         }
>
> @@ -954,6 +956,7 @@ static int pca953x_probe(struct i2c_client *client,
>         chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
>         if (chip == NULL)
>                 return -ENOMEM;
> +       chip->is_in_suspend = 0;
>
>         pdata = dev_get_platdata(&client->dev);
>         if (pdata) {
> @@ -1161,6 +1164,8 @@ static int pca953x_suspend(struct device *dev)
>         else
>                 regulator_disable(chip->regulator);
>
> +       chip->is_in_suspend = 1;
> +
>         return 0;
>  }
>
> @@ -1189,6 +1194,8 @@ static int pca953x_resume(struct device *dev)
>                 return ret;
>         }
>
> +       chip->is_in_suspend = 0;
> +
>         return 0;
>  }
>  #endif
> --
> 2.25.1
>

Can you elaborate more on the circumstances in which you're seeing this?

Bart

Re: [PATCH] driver: pca953x: avoid error message when resuming

[Andy Shevchenko]

On Mon, Mar 7, 2022 at 5:04 PM Alifer Moraes <alifer.m@variscite.com> wrote:
>
> From: FrancescoFerraro <francesco.f@variscite.com>
>
> Avoids the error messages "pca953x 1-0020: failed reading register"
> when resuming from suspend using gpio-key attached to pca9534.

Thanks for your report and fix. My comments below.

First of all, how many of them do you get and why is it a problem?

...

>         const struct pca953x_reg_config *regs;
> +       int is_in_suspend;

Usually we call it is_suspended or so, check existing code by `git
grep ...`. And it can be boolean.

...

>         ret = regmap_bulk_read(chip->regmap, regaddr, value, NBANK(chip));
>         if (ret < 0) {
> -               dev_err(&chip->client->dev, "failed reading register\n");
> +               if (!chip->is_in_suspend)
> +                       dev_err(&chip->client->dev, "failed reading register\n");

Hmm... Maybe we can simply move it to debug level?

>                 return ret;
>         }

...

>         chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
>         if (chip == NULL)
>                 return -ENOMEM;

> +       chip->is_in_suspend = 0;

Redundant change.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] driver: pca953x: avoid error message when resuming

[Pierluigi Passaro]

Hi All,

> > From: FrancescoFerraro <francesco.f@variscite.com>
> >
> > Avoids the error messages "pca953x 1-0020: failed reading register"
> > when resuming from suspend using gpio-key attached to pca9534.
> Thanks for your report and fix. My comments below.
> First of all, how many of them do you get and why is it a problem?
> ...

The number of occurrences depends on the time required to I2C bus to fully wake-up.
It's not a real problem, but the message may lead to think about a real I2C problem.

> >         const struct pca953x_reg_config *regs;
> > +       int is_in_suspend;
> Usually we call it is_suspended or so, check existing code by `git
> grep ...`. And it can be boolean.
> ...

Do you mean something like in drivers/gpio/gpio-omap.c ?

> >         ret = regmap_bulk_read(chip->regmap, regaddr, value, NBANK(chip));
> >         if (ret < 0) {
> > -               dev_err(&chip->client->dev, "failed reading register\n");
> > +               if (!chip->is_in_suspend)
> > +                       dev_err(&chip->client->dev, "failed reading register\n");
> Hmm... Maybe we can simply move it to debug level?

On the other side, this can be a serious problem, so I'm not sure the level should be changed. 

> >                 return ret;
> >         }
> ...
> >         chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> >         if (chip == NULL)
> >                 return -ENOMEM;
> > +       chip->is_in_suspend = 0;
> Redundant change.
> -- 
> With Best Regards,
> Andy Shevchenko

Thanks
Best Regards
Pier

Re: [PATCH] driver: pca953x: avoid error message when resuming

[Andy Shevchenko]

On Mon, Jun 20, 2022 at 4:18 PM Pierluigi Passaro
<pierluigi.p@variscite.com> wrote:

...

> > > Avoids the error messages "pca953x 1-0020: failed reading register"
> > > when resuming from suspend using gpio-key attached to pca9534.
> > Thanks for your report and fix. My comments below.
> > First of all, how many of them do you get and why is it a problem?
>
> The number of occurrences depends on the time required to I2C bus to fully wake-up.
> It's not a real problem, but the message may lead to think about a real I2C problem.

Wolfram, do we have any mechanisms that guarantees that I2C traffic is
not going on a semi-woken up host controller?

Writing this, I'm in doubt this patch is a fix we want. Wouldn't it
just hide the real issue with some resume ordering?

...

> > > +       int is_in_suspend;
> > Usually we call it is_suspended or so, check existing code by `git
> > grep ...`. And it can be boolean.
>
> Do you mean soomething like in drivers/gpio/gpio-omap.c ?

I believe almost any from the list `git grep -nl -w is_suspended` will suffice.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] driver: pca953x: avoid error message when resuming

[Linus Walleij]

On Mon, Jun 20, 2022 at 6:03 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Mon, Jun 20, 2022 at 4:18 PM Pierluigi Passaro
> <pierluigi.p@variscite.com> wrote:

> > > > Avoids the error messages "pca953x 1-0020: failed reading register"
> > > > when resuming from suspend using gpio-key attached to pca9534.
> > > Thanks for your report and fix. My comments below.
> > > First of all, how many of them do you get and why is it a problem?
> >
> > The number of occurrences depends on the time required to I2C bus to fully wake-up.
> > It's not a real problem, but the message may lead to think about a real I2C problem.
>
> Wolfram, do we have any mechanisms that guarantees that I2C traffic is
> not going on a semi-woken up host controller?
>
> Writing this, I'm in doubt this patch is a fix we want. Wouldn't it
> just hide the real issue with some resume ordering?

That sounds like a bug in the pm routines in the I2C driver. Why is it
returning from [runtime_]resume() if it is not properly resumed?

Yours,
Linus Walleij