probe gets called without i2c device

probe gets called without i2c device

[MUHAMMED ASAD P T]

Hi all,

 

 We didn't connect our i2c device with our board. But kernel driver

 subsystem calls the probe function from driver code. How to debug the

 issue.



our observation is as follows,

 

 In driver, if we comment out the .id_table in driver struct, then it

 is not loaded. When the device is connected or not, both the time, the

 driver is not loaded.








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probe gets called without i2c device

[Greg KH]

On Fri, Mar 23, 2018 at 05:47:01PM +0530, MUHAMMED ASAD P T wrote:
> Hi all,
> 
>  
> 
>  We didn't connect our i2c device with our board. But kernel driver
> 
>  subsystem calls the probe function from driver code. How to debug the
> 
>  issue.
> 
> 
> 
> our observation is as follows,
> 
>  
> 
>  In driver, if we comment out the .id_table in driver struct, then it
>  is not loaded. When the device is connected or not, both the time, the
>  driver is not loaded.

i2c is not a "hotplug" bus, so how would your device be found in order
to know to load it or not?

Shouldn't you have some device tree information that knows to bind your
device to the driver properly?

good luck!

greg k-h

probe gets called without i2c device

[MUHAMMED ASAD P T]

Hi Greg,



Thanks for the reply. 



We have the device tree information and wrote in the board. In this device tree, we specify our I2c device details. 

In usual, if the device is there, then driver probe gets called. This is the proper scenario.

But if the device is not there, then i2c master controller will not get the Ack from slave device. Still driver probe gets called without device

 connected (In device tree, device node is there for slave device). 

How the driver probe gets called?? This is the problem for us. 



Thanks & Regards

- Asad

  IQ Root Technologies






---- On Fri, 23 Mar 2018 17:57:31 +0530 Greg KH <greg at kroah.com> wrote ----




On Fri, Mar 23, 2018 at 05:47:01PM +0530, MUHAMMED ASAD P T wrote: 

> Hi all, 

> 

> 

> 

> We didn't connect our i2c device with our board. But kernel driver 

> 

> subsystem calls the probe function from driver code. How to debug the 

> 

> issue. 

> 

> 

> 

> our observation is as follows, 

> 

> 

> 

> In driver, if we comment out the .id_table in driver struct, then it 

> is not loaded. When the device is connected or not, both the time, the 

> driver is not loaded. 

 

i2c is not a "hotplug" bus, so how would your device be found in order 

to know to load it or not? 

 

Shouldn't you have some device tree information that knows to bind your 

device to the driver properly? 

 

good luck! 

 

greg k-h 

 

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probe gets called without i2c device

[valdis.kletnieks at vt.edu]

On Fri, 23 Mar 2018 19:07:41 +0530, MUHAMMED ASAD P T said:
> We have the device tree information and wrote in the board. In this device
> tree, we specify our I2c device details.

So you told the kernel the device is there.

> In usual, if the device is there, then driver probe gets called. This is the proper scenario.

So the kernel acts like it's there.

> But if the device is not there, then i2c master controller will not get the
> Ack from slave device. Still driver probe gets called without device
>  connected (In device tree, device node is there for slave device).

Why is the slave listed if it isn't actually present and wired up?

> How the driver probe gets called?? This is the problem for us.

Maybe if you don't want the driver called if the device isn't there, you
shouldn't lie to the kernel and write a device tree entry that says it *is*
there.

Just a thought...
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probe gets called without i2c device

[MUHAMMED ASAD P T]

Hi all,



We didn't connect our i2c device with our board. But kernel driver subsystem calls the probe function from driver code. How to debug the issue.









Thanks & Regards

- Asad

  IQ Root Technologies





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