[meta-xilinx] Zynq XADC

[MUGRIDGE Robin]

> -----Original Message-----

> From: Sören Brinkmann [mailto:soren.brinkmann at xilinx.com]

> Sent: 18 May 2015 15:42

> To: MUGRIDGE Robin

> Cc: meta-xilinx at yoctoproject.org

> Subject: Re: [meta-xilinx] Zynq XADC

>

> On Mon, 2015-05-18 at 11:31AM +0000, MUGRIDGE Robin wrote:

> >    Hi,

> >

> >

> >

> >    I am having an issue trying to use the Zynq XADC after a linux reboot.  On

> >    power up, I can access the XADC in the FSBL.  If I stop the boot in u-boot

> >    and issue a reset command, I can still access the XADC from the FSBL.

> >    However, if I let linux start and then issue a reboot command, the XADC

> no

> >    longer works in the FSBL (the XAdcPs_SelfTest function fails – all XADC

> >    register reads return 0).

> >

> >

> >

> >    I’m using Dizzy.  If it has anything to do with it, I’m not configuring

> >    the PL at boot – this is done after linux starts.

> >

> >

> >

> >    Is there anything I need to do to allow the XADC to work after linux has

> >    been running?

>

> Are you accessing the device through its driver or some other path? The

> symptoms sound suspiciously like the device's clock isn't enabled.

> Usually the driver is supposed to handle that though. Could you check the

> state of the PCAP clock in /sys/kernel/debug/clk/clk_summary?

>



I haven't (yet) tried to access the XADC from linux - I will need to do this, so if enabling it in linux is likely to help a pointer on what to do would help!



The only reference to the PCAP in clk_summary is...



   clock                        enable_cnt  prepare_cnt  rate        accuracy

---------------------------------------------------------------------------------

          pcap_mux              1           1            999999990  0

             pcap_div           1           1            199999998  0

                pcap            1           2            199999998  0






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