PCI Radeon RV100 detection hang on sparc64

[David Miller]

From: Adam Jackson <ajax at redhat.com>
Date: Thu, 06 Sep 2012 12:51:17 -0400

> On Thu, 2012-09-06 at 17:41 +0300, Meelis Roos wrote:
> 
>> And here the machine hangs. Debugging printk-s reveal that it does not 
>> find any active I/O port resources and then continues into initializing 
>> the card. Down in igp_read_bios_from_vram() it successfully ioremaps 
>> memory region 0 (vram_base=1ff08000000 and size=40000) and tries to read 
>> 2 bytes from there and hangs on reading bios[0].
> 
> This is probably because...

I think the real issue is that the VRAM bios reading code is buggy, see
my other email.  It deferences ioremap()'d memory, and that's not allowed.

One must use the proper __iomem pointer accessors, such as readl(), readb(),
etc.