[meta-xilinx] Zynq I2C Problem

[Mike Looijmans]

Classic mistake. Been there, done that :)

Activating the internal pull-ups of the Zynq IO pins is usually enough for I2C.


On 10-08-15 14:08, MUGRIDGE Robin wrote:
> Hi,
>
> Turned out this was a lack of pull-ups on the board!
>
> Thanks,
>
> Robin
>
> *From:*meta-xilinx-bounces at yoctoproject.org
> [mailto:meta-xilinx-bounces at yoctoproject.org] *On Behalf Of *MUGRIDGE Robin
> *Sent:* 10 August 2015 11:30
> *To:* meta-xilinx at yoctoproject.org
> *Subject:* SPOOFED: [meta-xilinx] Zynq I2C Problem
>
> Hi,
>
> I am using linux-xlnx 3.14 (fido) with the Zynq and have an issue with the I2C
> peripheral using the cdns (r1p10) module.
>
> Our design connects to an external I2C device and we try to identify that
> device by reading a register from it.  If the device is not connected when the
> read is performed, the transaction fails with “cdns-i2c e0004000.ps7-i2c:
> timeout waiting on completion” being output on the console.  After this, all
> i2c transactions using the i2c0 (e0004000) peripheral fail with “Resource
> temporarily unavailable”.
>
> I’ve debugged into the cdns module and the call to wait_for_completion_timeout
> in cdns_i2c_process_msg returns zero (which is fine), but the SR register  has
> the value 0x00000140 before the cdns_i2c_master_reset call and 0x00000100
> afterwards. This is the bus active (BA) bit which is causing the subsequent
> transactions to be failed.
>
> How can I get to reset the BA bit?
>
> Incidentally, the cdns_i2c_master_reset method writes to the read only SR
> register!
>
> I’ve had a look at the latest code in mainline but can’t see that this would
> be any different.
>
> Thanks,
>
> Robin
>
>
>
> 

Kind regards,

Mike Looijmans
System Expert

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