Re: Problem with I2c-4 bus and Kernel 3.0.8.

[David Anders]

Randy,

the primary issues with some of the older kernels revolve around the i2c char driver support. however the ds1307 does not use the char driver. based on your debug message report i would suspect that either you have the bus tied to the wrong voltage, or you have incorrect value or missing pullups on the bus.

i'll be happy to review your schematic and source code....

Dave

On Wednesday, August 1, 2012 4:12:00 PM UTC-5, Randy Graham wrote:

Hello,

 

Are there any known issues using an I2C slave device on the I2C-4 bus of a pandaboard ES running kernel 3.0.8 ?

 

I have extensively googled and found a reference to possible issues with I2C char driver support, but wanted to ask here if anyone had any direct experience with this.

 

I am interfacing a mcp7940x RTC module to a pandaboard ES 3.0.8 running kernel 3.0.08 with Android ICS, all built from source.

I have modified my board file to include my I2C device, and it is being probed at boot time.

However, during probe the following call returns error -121, which is either a BUSY or REMOTEIO error.

 

ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf); // returns -121

 

I have the same RTC module working with a raspberrypi board running a 3.2x kernel so I am sure that the RTC is working correctly.

 

I have also confirmed that my RTC is connected correctly to the I2C-4 bus and I am pretty sure that my board file is configured correctly for my I2C device.

 

I'd appreciate hearing from anyone who may have some experience with this before I try to update my kernel.

 

-Randy

 

[Randy Graham]

Thanks Dave.

 

My hardware guy checked everything out and says it all looks good, including voltages.

The next step will be to scope the i2c lines.

 

Thanks for the hint that at least the char driver issue is not the problem, I'll stop hunting down that path.

 

-Randy

 

 

 

 

 

[Randy Graham]