Hi Guenter-san, Thank you so much for the explanation. I could understand enough it. I will abandon these patches for now.
> What is an "I2C error unit" ? The error unit is caused by the I2C isolator failure device then bad I2C signals causes the error. Our products have been replaced the device to other new device for the manufacturing. But still there are many units using the old device and it is possible to be caused the failure behavior in future. We tried to change the I2C clock speed on the error unit but the issue was not able to be resolved. By the way we have fixed our original user space driver for other feature to retry for the error. > Yes, the driver should check for errors, but it should report all errors > to user space and neither retry nor silently hide/ignore errors (unless > a problem is known to be a chip problem). I will do consider this in future. But at first I will investigate the cause of another voltage warning issue at first. It is not caused by the I2C error but sometimes detected the voltage warning actually. Regards, Ikegami > -----Original Message----- > From: Guenter Roeck [mailto:[email protected]] On Behalf Of Guenter > Roeck > Sent: Thursday, July 12, 2018 1:23 PM > To: IKEGAMI Tokunori; Jean Delvare > Cc: PACKHAM Chris; [email protected] > Subject: Re: [PATCH 3/5] hwmon: adt7475: Change to use adt7475_read macro > > On 07/11/2018 09:01 PM, IKEGAMI Tokunori wrote: > > Hi Guenter-san, > > > > Thank you so much for your comments. > > > > Oh I see and actually we have some I2C error units in our products. > > The patch is for the error case mainly. > > What is an "I2C error unit" ? > > > But I think that sometimes the I2C error is still caused on the normal > units also actually. > > I am not sure about that the normal units error behavior is caused by > the board (I2C controller) or the chip ADT7476A but probably the former > but not sure. > > So should these patches not be applied to the adt7475 driver as you > mentioned? > > > > Drivers are not responsible for handling bad board behavior, so retries > due to controller or board issues should not be handled by the chip > driver. > Otherwise we would end up having to sprinkle retries into all i2c drivers > in the kernel. > > If the problem is caused by the controller, it should be handled in the > controller driver. If the problem is caused by bad i2c signals, it should > be handled by hardware (or maybe by selecting a different clock speed). > > > At first I thought that the I2C SMBus APIs return error codes but adt7475 > driver does not check so it should be checked the error codes. > > Is this not correct? > > > > Yes, the driver should check for errors, but it should report all errors > to user space and neither retry nor silently hide/ignore errors (unless > a problem is known to be a chip problem). > > Guenter > > > To make sure let me confirm above. > > > > Regards, > > Ikegami > > > >> -----Original Message----- > >> From: [email protected] > >> [mailto:[email protected]] On Behalf Of Guenter > Roeck > >> Sent: Thursday, July 12, 2018 12:42 PM > >> To: IKEGAMI Tokunori; Jean Delvare > >> Cc: PACKHAM Chris; [email protected] > >> Subject: Re: [PATCH 3/5] hwmon: adt7475: Change to use adt7475_read > macro > >> > >> On 07/11/2018 07:52 PM, IKEGAMI Tokunori wrote: > >>> Hi Guenter-san, > >>> > >>> Thank you so much for your comments. > >>> Okay now I am thinking to change the adt7475_read macro to a function > >> to repeat for the error case. > >>> If you have any comment about this please let me know. > >> > >> Yes - we should only do this if it is known to be a chip problem. > >> Patching the chip driver for a board (or i2c controller) problem > >> is not appropriate. > >> > >> Guenter > >> > >>> Anyway I will do send v2 version patches later. > >>> > >>> Regards, > >>> Ikegami > >>> > >>>> -----Original Message----- > >>>> From: Guenter Roeck [mailto:[email protected]] On Behalf Of Guenter > >>>> Roeck > >>>> Sent: Thursday, July 12, 2018 10:50 AM > >>>> To: IKEGAMI Tokunori; Jean Delvare > >>>> Cc: PACKHAM Chris; [email protected] > >>>> Subject: Re: [PATCH 3/5] hwmon: adt7475: Change to use adt7475_read > >> macro > >>>> > >>>> On 07/11/2018 06:04 PM, Tokunori Ikegami wrote: > >>>>> It shoudl be same as with other functions to use adt7475_read. > >>>>> So change to use it instead of i2c_smbus_read_byte_data. > >>>>> > >>>> > >>>> I don't see a point in this change. Replacing a function name doesn't > >>>> make > >>>> the code easier to read. If anything, you could consider dropping > >>>> adt7475_read > >>>> and calling i2c_smbus_read_byte_data() directly. > >>>> > >>>> Guenter > >>>> > >>>>> Signed-off-by: Tokunori Ikegami <[email protected]> > >>>>> Cc: Chris Packham <[email protected]> > >>>>> Cc: [email protected] > >>>>> --- > >>>>> drivers/hwmon/adt7475.c | 2 +- > >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>>> > >>>>> diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c > >>>>> index a40eb62ee6b1..bad250729e99 100644 > >>>>> --- a/drivers/hwmon/adt7475.c > >>>>> +++ b/drivers/hwmon/adt7475.c > >>>>> @@ -1012,7 +1012,7 @@ static ssize_t > >>>> pwm_use_point2_pwm_at_crit_store(struct device *dev, > >>>>> return -EINVAL; > >>>>> > >>>>> mutex_lock(&data->lock); > >>>>> - data->config4 = i2c_smbus_read_byte_data(client, > >>>> REG_CONFIG4); > >>>>> + data->config4 = adt7475_read(REG_CONFIG4); > >>>>> if (val) > >>>>> data->config4 |= CONFIG4_MAXDUTY; > >>>>> else > >>>>> > >>> > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" > >> in > >> the body of a message to [email protected] > >> More majordomo info at http://vger.kernel.org/majordomo-info.html N�����r��y���b�X��ǧv�^�){.n�+����{�� ��)���w* jg��� �����ݢj/���z�ޖ��2�ޙ���&�)ߡ�a���� �G���h��j:+v���w�٥
