Thanks for the suggestion !! On Wed, Aug 30, 2023 at 8:56 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > Pankaj, > > On 8/30/23 02:28, Pankaj Pandey wrote: > > Hi Guenter, > > > > Thanks for the pointer. Actually during bmr454 probing during kernel boots-up it > > called system reset/crash. For reference please find bmr454 probing log below: > > > > First of all, please don't top-post. > > > [ 14.910630] pmbus 7-0010: bmr454 BMR status word : 0x2 > > [ 14.922945] pmbus 7-0010: bmr454 BMR status cml : 0x2 > > > > Bit 1 of the CML status register suggests that there is a communication > problem. Per PMBus standard: > > Bit 1 - A communication fault other than the ones listed in this table has occurred > > > ---> Immediately after above bmr454 probing it reset/crash the system > > and jump to u-boot. > > > > I don't think anything _called_ system reset/crash. There is no code > in the driver that would do that. > > > Using debug prints I observed system got resettted after reaching to > > _pmbus_write_byte function. But > > sometimes probing is fine, not observing any system reset/crash. > > > > My best guess is that the i2c communication with the chip is unstable, > and that the write causes it to do something that causes the reset. > How it would do that - I don't know. Maybe one of the module pins is wired > to the system's reset pin (though I can not imagine why that would be > the case), or the miscommunication causes a chip reset. Either case, > maybe the problem is in the I2C bus speed. If you can, I would suggest > to lower it to 100 KHz to see if that makes a difference. > > Guenter > > > > Regards, > > Pankaj Pandey > > > > > > On Wed, Aug 30, 2023 at 7:38 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > >> > >> On Wed, Aug 30, 2023 at 07:16:46AM +0530, Pankaj Pandey wrote: > >>> ---------- Forwarded message --------- > >>> From: Pankaj Pandey <pankaj.embedded@xxxxxxxxx> > >>> Date: Wed, Aug 30, 2023 at 4:42 AM > >>> Subject: Regarding pmbus_core.c > >>> To: <linux@xxxxxxxxxxxx> > >>> > >>> > >>> Hi Guenter Roeck, > >>> > >>> I am facing an issue at drivers/hwmon/pmbus/pmbus_core.c of linux-5.10 kernel. > >>> I am using the bm454 driver from drivers/hwmon/pmbus/pmbus.c. > >>> Observed sometimes my Powepc based target board called for reset from > >>> inside int pmbus_write_byte_data(struct i2c_client *client, int page, > >>> u8 reg, u8 value) function. It is not consistent, sometimes not > >> > >> Sorry, I don't understand what you mean with "called for reset from > >> inside int pmbus_write_byte_data". Please clarify. > >> > >> If I recall correctly, bmr454 is very picky when it comes to i2c bus > >> speed. If it acts up, you might have some success with picking a different > >> bus speed. > >> > >> Thanks, > >> Guenter > >> > >>> observed any reset and bmr454 initialized fine. Please suggest any > >>> pointers to debug this issue. > >>> > >>> Regards, > >>> Pankaj Pandey >
