This is probably a Timur question, but any enlightment is appreciated. This
concerns Linux-2.6.17.11 from kernel.org with some modifications for our custom
8541 board. The original BSP was evolved from mpc85xx_cds.
Down in the guts of arch/ppc/syslib/ppc85xx_seteup.c is a routine called
mpc85xx_setup_pci1(). In this routine we do an assignment of some outbound
window registers and I am most interested in POTAR2, POWAR2 & POWBAR2 right now.
This routine uses a ccsr_pci struct to assign potar2, powar2, powbar2 and
others like this:
pci->potar2 = 0x00100000;
pci->powar2 = 0x8004401a;
pci->powbar2 = 0x00888000;
Where I have changed the constants for our board. The issue is that when I call
readl to read back these same registers at the end of this same subroutine, I
get into endianess issues. That is, I read back
POTAR2 == 0x00001000
POWAR2 == 0x1A400480
POWBAR2 == 0x00800800
Where the four bytes in each 32bit word are now exchanged so that 80_04_40_1A
became 1A_40_04_80.
I understand big versus little endian, that isn't the question. The question is
"What is really in the POTAR2, POWAR2 & POWBAR2 registers and how can I prove
that what is in the registers is really what I wish to be in the registers?"
It may be that one or more endian swap things are going on within Linux and I
have inherited some source from others, so actually proving what is in the
registers is becoming important.
Charles
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