Reputation: 41032
printk(" start = %p , end = %p \n",res->start ,res->end );
fbi->reg_base = ioremap_nocache(res->start, res->end - res->start);
printk(" fbi->reg_base = %p \n",fbi->reg_base);
printk(" virt_to_phys(fbi->reg_base) = %p \n", virt_to_phys(fbi->reg_base));
printk(" virt_to_bus(fbi->reg_base) = %p \n", virt_to_bus(fbi->reg_base));
The output is
start = 72100000 , end = 72100fff
fbi->reg_base = 70b10000
virt_to_phys(fbi->reg_base) = a0b10000
virt_to_phys(fbi->reg_base) = a0b10000
Why don't I get back the 0x72100000
?
Upvotes: 0
Views: 465
Reputation: 63320
I would imagine you don't get back that address because the address that ioremap_nocache
returns isn't guaranteed to be a virtual address, as it says here:
ioremap_nocache performs a platform specific sequence of operations to make bus memory CPU accessible via the readb/readw/readl/writeb/ writew/writel functions and the other mmio helpers. The returned address is not guaranteed to be usable directly as a virtual address.
Upvotes: 1