On 26.06.2024 09:23, Biju Das wrote:
>
>
>> -----Original Message-----
>> From: claudiu beznea <claudiu.beznea@xxxxxxxxx>
>> Sent: Wednesday, June 26, 2024 7:14 AM
>> To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>; Chris Brandt <Chris.Brandt@xxxxxxxxxxx>;
>> andi.shyti@xxxxxxxxxx; robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
>> geert+renesas@xxxxxxxxx; magnus.damm@xxxxxxxxx; mturquette@xxxxxxxxxxxx; sboyd@xxxxxxxxxx;
>> p.zabel@xxxxxxxxxxxxxx; wsa+renesas@xxxxxxxxxxxxxxxxxxxx
>> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
>> linux-kernel@xxxxxxxxxxxxxxx; linux-clk@xxxxxxxxxxxxxxx; Claudiu Beznea
>> <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>> 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@xxxxxxxxx>
>>>> 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@xxxxxxxxxxxxxx>
>>>>
>>>> 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@xxxxxxxxxxxxxx>
>>>> ---
>>>>
>>>> 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.
>
> WARN_ON_ONCE() should be ok I guess as people are using for printing this info only once??
Ok, I'm leaving this to I2C maintainers.
Andi, Wolfram,
Would you prefer having WARN_ON_ONCE() instead of dev_err() for potential
failures of pm_runtime_resume_and_get()?
Thank you,
Claudiu Beznea
>
> Currently we don't know how to trigger pm_runtime_resume_and_get() error
> condition in our setup using a testapp and we are expecting an error may
> happen in future. If at all there is an error in future, we need detailed
> error info so that we can handle it and fix the bug.
>
> Cheers,
> Biju
>
>>
>> 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
>>>>
>>>
