[U-Boot-Users] PCI access memory space
wd at denx.de
Tue Jan 17 19:10:35 CET 2006
In message <000101c61b7e$5c942600$d901a8c0 at SN8032> you wrote:
> I'm using on my custom board (PPC 440GX) an ATI M6-C16H Mobility Radeon
> video card. I work with U-boot 1.1.2.
> I can access the configuration space of ATI with the functions:
> pci_read_config_dword(..) and pci_write_config_dword(.)
You can also test this using simple "md" and "mw" commands.
> Now I have to access the memory space of the ATI. I use the functions:
> readl(.) and writel(..)
> But when I start u-boot, it hangs. I can not access the memory base address
> of the ATI.
This is more or less to be expected.
> Can someone please give me information how U-Boot handles with PCI devices
> when accessing the memory space.
This has nothing to do with U-Boot or PCI accesses. Your problem is
most probably that the ATI graphics card expects that it's memory
controller gets initialized - which is normally done by the (x86)
BIOS code of the card. Without such initialization you simply cannot
access the RAM on the card - which is what's causing your hang --
exactly like your system will hang if you try to access the on-board
DRAm without proper initialization.
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
When a man sits with a pretty girl for an hour, it seems like a
minute. But let him sit on a hot stove for a minute -- and it's lon-
ger than any hour. That's relativity. -- Albert Einstein
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