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Revision fec59a711eef002d4ef9eb8de09dd0a26986eb77 authored by John W. Linville on 05 August 2005, 01:06:10 UTC, committed by Linus Torvalds on 05 August 2005, 04:32:46 UTC 
[PATCH] PCI: restore BAR values after D3hot->D0 for devices that need it
 
Some PCI devices (e.g. 3c905B, 3c556B) lose all configuration
(including BARs) when transitioning from D3hot->D0.  This leaves such
a device in an inaccessible state.  The patch below causes the BARs
to be restored when enabling such a device, so that its driver will
be able to access it.

The patch also adds pci_restore_bars as a new global symbol, and adds a
correpsonding EXPORT_SYMBOL_GPL for that.

Some firmware (e.g. Thinkpad T21) leaves devices in D3hot after a
(re)boot.  Most drivers call pci_enable_device very early, so devices
left in D3hot that lose configuration during the D3hot->D0 transition
will be inaccessible to their drivers.

Drivers could be modified to account for this, but it would
be difficult to know which drivers need modification.  This is
especially true since often many devices are covered by the same
driver.  It likely would be necessary to replicate code across dozens
of drivers.

The patch below should trigger only when transitioning from D3hot->D0
(or at boot), and only for devices that have the "no soft reset" bit
cleared in the PM control register.  I believe it is safe to include
this patch as part of the PCI infrastructure.

The cleanest implementation of pci_restore_bars was to call
pci_update_resource.  Unfortunately, that does not currently exist
for the sparc64 architecture.  The patch below includes a null
implemenation of pci_update_resource for sparc64.

Some have expressed interest in making general use of the the
pci_restore_bars function, so that has been exported to GPL licensed
modules.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent c306895
Raw File
initramfs_data.S 
/*
  initramfs_data includes the compressed binary that is the
  filesystem used for early user space.
  Note: Older versions of "as" (prior to binutils 2.11.90.0.23
  released on 2001-07-14) dit not support .incbin.
  If you are forced to use older binutils than that then the
  following trick can be applied to create the resulting binary:


  ld -m elf_i386  --format binary --oformat elf32-i386 -r \
  -T initramfs_data.scr initramfs_data.cpio.gz -o initramfs_data.o
   ld -m elf_i386  -r -o built-in.o initramfs_data.o

  initramfs_data.scr looks like this:
SECTIONS
{
       .init.ramfs : { *(.data) }
}

  The above example is for i386 - the parameters vary from architectures.
  Eventually look up LDFLAGS_BLOB in an older version of the
  arch/$(ARCH)/Makefile to see the flags used before .incbin was introduced.

  Using .incbin has the advantage over ld that the correct flags are set
  in the ELF header, as required by certain architectures.
*/

.section .init.ramfs,"a"
.incbin "usr/initramfs_data.cpio.gz"
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