AM3352 GPMC config question

I have a question about AM3352 GPMC config.

I configed GPMC_CS_CONFIG1 to 7, base address 0x50000000 with ioremap first.

But my linux crash at:

Uncompressing Linux... done, booting the kernel.

I found it related to one bit, if I write 0xf19 to config7, no issue, but later other issue since cs is not enabled.

If I write 0xf59 to config7, linux crash.

What could be the problem?

And is there a way to check the content of register directly (not using ioremap), so I know the write content is correct?

Thanks.