OMAP-L138: ARM and DSP crash when I put the chip into PLL bypass mode

Part Number:OMAP-L138

Hi,

I'm trying to learn to change the PLL clock settings on my OMAP-L138 chip. By default, it runs with 300 MHz (OSCIN=24MHz, PLLM=24+1, POSTDIV=1+1), and I'd like to change that to, say, 150 MHz (by setting POSTDIV=3+1). To that end, I followed the instructions in OMAP-L138 Technical Reference Guide (sec.8.2.2.3).

But my code crashes when I clear the PLLEN bit, which puts the chip into bypass mode.

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After the line #32 (the DSP code is attached), nothing is printed by UART. Could it be becuase I'm doing something wrong (for example, I clear EXTCLKSRC bit to select OSCIN as the external clock before clearing PLLEN, but the guide says "program the EXTCLKSRC bit", it doesn't tell if it should be set or cleared) or because somehow UART gets broken after changing the clock. The U-Boot (ARM) doesn't respond in that state, either, by the way.

Thanks in advance,

Silacko