linux-kernel - RE: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and

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Date: Tue, 25 Jun 2024 15:53:27 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Claudiu.Beznea <claudiu.beznea@...on.dev>, Chris Brandt
	<Chris.Brandt@...esas.com>, "andi.shyti@...nel.org" <andi.shyti@...nel.org>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"geert+renesas@...der.be" <geert+renesas@...der.be>, "magnus.damm@...il.com"
	<magnus.damm@...il.com>, "mturquette@...libre.com" <mturquette@...libre.com>,
	"sboyd@...nel.org" <sboyd@...nel.org>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, "wsa+renesas@...g-engineering.com"
	<wsa+renesas@...g-engineering.com>
CC: "linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, Claudiu.Beznea
	<claudiu.beznea@...on.dev>, Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: RE: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and_get()

Hi Claudiu,

> -----Original Message-----
> From: Claudiu <claudiu.beznea@...on.dev>
> Sent: Tuesday, June 25, 2024 1:14 PM
> Subject: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and_get()
> 
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> pm_runtime_get_sync() may return with error. In case it returns with error
> dev->power.usage_count needs to be decremented.
> dev->pm_runtime_resume_and_get()
> takes care of this. Thus use it.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
> 
> Changes in v2:
> - delete i2c adapter all the time in remove
> 
>  drivers/i2c/busses/i2c-riic.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c index
> 83e4d5e14ab6..002b11b020fa 100644
> --- a/drivers/i2c/busses/i2c-riic.c
> +++ b/drivers/i2c/busses/i2c-riic.c
> @@ -113,6 +113,8 @@ struct riic_irq_desc {
>  	char *name;
>  };
> 
> +static const char * const riic_rpm_err_msg = "Failed to runtime
> +resume";
> +
>  static inline void riic_writeb(struct riic_dev *riic, u8 val, u8 offset)  {
>  	writeb(val, riic->base + riic->info->regs[offset]); @@ -133,10 +135,14 @@ static int
> riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  	struct riic_dev *riic = i2c_get_adapdata(adap);
>  	struct device *dev = adap->dev.parent;
>  	unsigned long time_left;
> -	int i;
> +	int i, ret;
>  	u8 start_bit;
> 
> -	pm_runtime_get_sync(dev);
> +	ret = pm_runtime_resume_and_get(dev);
> +	if (ret) {
> +		dev_err(dev, riic_rpm_err_msg);

As at the moment we don't know how to reproduce this error condition
Can we use WARN_ON_ONCE() instead to catch detailed error condition here??

Cheers,
Biju

> +		return ret;
> +	}
> 
>  	if (riic_readb(riic, RIIC_ICCR2) & ICCR2_BBSY) {
>  		riic->err = -EBUSY;
> @@ -301,6 +307,7 @@ static const struct i2c_algorithm riic_algo = {
> 
>  static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)  {
> +	int ret;
>  	unsigned long rate;
>  	int total_ticks, cks, brl, brh;
>  	struct device *dev = riic->adapter.dev.parent; @@ -379,7 +386,11 @@ static int
> riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
>  		 t->scl_fall_ns / (1000000000 / rate),
>  		 t->scl_rise_ns / (1000000000 / rate), cks, brl, brh);
> 
> -	pm_runtime_get_sync(dev);
> +	ret = pm_runtime_resume_and_get(dev);
> +	if (ret) {
> +		dev_err(dev, riic_rpm_err_msg);
> +		return ret;
> +	}
> 
>  	/* Changing the order of accessing IICRST and ICE may break things! */
>  	riic_writeb(riic, ICCR1_IICRST | ICCR1_SOWP, RIIC_ICCR1); @@ -498,11 +509,18 @@ static void
> riic_i2c_remove(struct platform_device *pdev)  {
>  	struct riic_dev *riic = platform_get_drvdata(pdev);
>  	struct device *dev = &pdev->dev;
> +	int ret;
> 
> -	pm_runtime_get_sync(dev);
> -	riic_writeb(riic, 0, RIIC_ICIER);
> -	pm_runtime_put(dev);
>  	i2c_del_adapter(&riic->adapter);
> +
> +	ret = pm_runtime_resume_and_get(dev);
> +	if (ret) {
> +		dev_err(dev, riic_rpm_err_msg);
> +	} else {
> +		riic_writeb(riic, 0, RIIC_ICIER);
> +		pm_runtime_put(dev);
> +	}
> +
>  	pm_runtime_disable(dev);
>  }
> 
> --
> 2.39.2
>