linux/drivers/acpi/reboot.c
Linus Torvalds 19244ad06b Revert "ACPI: ignore FADT reset-reg-sup flag"
This reverts commit cf450136bf.

It breaks reboot on at least one Thinkpad T43, as reported by Jörg Otte:
 "On reboot it shuts down as normal.
  The last lines displayed are:

  >Unmounting temporary filesystems.. [OK]
  >Deactivating swap...               [OK]
  >Unmounting local filesystems...    [OK]
  >Will now restart
  >    Restarting system

  Then I hear it accessing the cd-drive, but then it's being stuck."

Jörg bisected the regression to this commit.

That commit fixes another machine (see

  https://bugzilla.kernel.org/show_bug.cgi?id=11533

for details) that has a BIOS bug and doesn't support ACPI reset.
However, at least one of those other reporters no longer even has the
machine in question, and had a different workaround to begin with.
Besides, it clearly was a buggy BIOS.  Let's not break the correct case
to fix that case.

Reported-and-bisected-by: Jörg Otte <jrg.otte@googlemail.com>
Cc: linux-acpi@vger.kernel.org
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-20 11:19:35 -07:00

54 lines
1.3 KiB
C

#include <linux/pci.h>
#include <linux/acpi.h>
#include <acpi/reboot.h>
void acpi_reboot(void)
{
struct acpi_generic_address *rr;
struct pci_bus *bus0;
u8 reset_value;
unsigned int devfn;
if (acpi_disabled)
return;
rr = &acpi_gbl_FADT.reset_register;
/* ACPI reset register was only introduced with v2 of the FADT */
if (acpi_gbl_FADT.header.revision < 2)
return;
/* Is the reset register supported? The spec says we should be
* checking the bit width and bit offset, but Windows ignores
* these fields */
if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER))
return;
reset_value = acpi_gbl_FADT.reset_value;
/* The reset register can only exist in I/O, Memory or PCI config space
* on a device on bus 0. */
switch (rr->space_id) {
case ACPI_ADR_SPACE_PCI_CONFIG:
/* The reset register can only live on bus 0. */
bus0 = pci_find_bus(0, 0);
if (!bus0)
return;
/* Form PCI device/function pair. */
devfn = PCI_DEVFN((rr->address >> 32) & 0xffff,
(rr->address >> 16) & 0xffff);
printk(KERN_DEBUG "Resetting with ACPI PCI RESET_REG.");
/* Write the value that resets us. */
pci_bus_write_config_byte(bus0, devfn,
(rr->address & 0xffff), reset_value);
break;
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
case ACPI_ADR_SPACE_SYSTEM_IO:
printk(KERN_DEBUG "ACPI MEMORY or I/O RESET_REG.\n");
acpi_reset();
break;
}
}