Question about mmc4 initialization on OMAP5432

[Chen Baozi <baozich@gmail.com>]

Hi all,

I have got a problem when booting dom0 kernel for Xen on OMAP5432 uEVM.
With a recent patch, Xen hypervisor is avoid to map "disabled" device
memory for dom0. In omap5-uevm.dts, we have got the &mmc4 node marked as
"disabled". So the Xen won't populate <0x480d1000 0x400> memory region
to the dom0. If dom0 is trying to access any memory address in this
area, the hypervisor would be panic with a tranlation fault. However, it
turns out that even the mmc4 is disabled in omap5-uevm.dts, Linux kernel
is trying to access the 0x480d1010 when booting, which then leads a
hypervisor panic as mentioned.

The only point I know right now is that the 0x480d1010 is accessed by
the omap_hwmod_read(). However, what makes me confused is how the dom0
kernel called omap_hwmod_read() to access 0x480d1010 while the mmc4 is
disabled. I guess it might relate to hard coded omap_hwmod structure but
have no idea what happen exactly when dom0 access the address due to the
lack of calling stack information when booting Xen hypervisor.

Thanks a lot.

Chen Baozi