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

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Message-ID: <14167607-e67b-4627-99f0-6e99acc7f880@tuxon.dev>
Date: Wed, 26 Jun 2024 09:13:42 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Biju Das <biju.das.jz@...renesas.com>,
 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.uj@...renesas.com>
Subject: Re: [PATCH v2 04/12] i2c: riic: Use pm_runtime_resume_and_get()

Hi, Biju,

On 25.06.2024 18:53, Biju Das wrote:
> 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??

[1] states "So, naturally, use of WARN_ON() is also now discouraged much of
the time". I've go with dev_err() or something similar.

Thank you,
Claudiu Beznea

[1] https://lwn.net/Articles/969923/

> 
> 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
>>
>