drivers:axi_core:axi_dac_core:axi_dac_core.c: Fix DAC init crash

[kylex2]

I have problems getting the no-OS code running on AD9364. It seems there's an issue with the axi_dac_init() code which gave me CPU exceptions (division by 0).

Only tested on AD9364 (ZedBoard+fmcomms4) and there it doesn't crash anymore.

dac->clock_hz needs to be set before axi_dac_dds_set_frequency() is run. axi_dac_data_setup() is calling axi_dac_dds_set_frequency(). Hence, we need to set dac->clock_hz before axi_dac_data_setup().

Move mdelay(100) so the frequency register value has time to stabilize after reset before reading.

[kylex2]

Ok, so I just checked the commit history. This bug seems to be introduced in commit 1bf45a05e50d13f0c73a6aa1bbe7e425e45f87f4. Before that commit the reset was done in axi_dac_init_begin(), the delay was after that call. Also the assigning of dac->clock_hz in axi_dac_init_finish() was made before calling axi_dac_data_setup().

I don't know in which functions you prefer to do what.

[kylex2]

Sure, please test it as much as possible. It should be safe to merge though since it basically restores behavior to before 1bf45a05e50d13f0c73a6aa1bbe7e425e45f87f4.

[kylex2]

Tried to resolve conflict with github tool but still said it had conflicts so I rebased to master and force pushed.

[buha]

Closing this for now, might reconsider adapting/testing later on.