Unable to read/write consistently to a device.

2 messages, 2 authors, 2001-02-27 · open the first message on its own page

Unable to read/write consistently to a device.

From: gopi krishna <hidden>
Date: 2001-02-27 17:02:38

Hi..

  We have custom board based on 860T running
linux2.2.14

  We have a device 0xf0040000.  This address has been
ioremapped.
(Hence directly using the physical address to access
the memory)

We tried to read the registers using:
  in_be32(addr)
  *address
  in_be32(volatile unsigned *addr)
but, none of them are giving any consistent results.

With BDM, we are able to get correct and consistent
results.

Can there be any cache/coherency/any other issues of
linux which we are overlooking?

thanx in advance
gopi


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Re: Unable to read/write consistently to a device.

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2001-02-27 19:27:29

 We have a device 0xf0040000.  This address has been
ioremapped.
(Hence directly using the physical address to access
the memory)
What do you mean by ioremapped ? You should use the virtual address
returned by ioremap (which is usually _not_ the same as the physical
address, except in some specific cases), not the physical address, to
access the registers.

Ben.

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
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