[patch 2.6.14-rc1] pci: only call pci_restore_bars at boot

John W. Linville
2005-09-14T13:52:42Z

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Certain (SGI?) ia64 boxes object to having their PCI BARs
restored unless absolutely necessary. This patch restricts calling
pci_restore_bars from pci_set_power_state unless the current state
is PCI_UNKNOWN, the actual (i.e. physical) state of the device is
PCI_D3hot, and the device indicates that it will lose its configuration
when transitioning to PCI_D0.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
---
Many thanks to Keith Owens <kaos@sgi.com> for a) narrowing-down the
problem; and, b) quickly testing the fix and reporting the results.

drivers/pci/pci.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -309,17 +309,25 @@ pci_set_power_state(struct pci_dev *dev,

pci_read_config_word(dev, pm + PCI_PM_CTRL, &pmcsr);

- /* If we're in D3, force entire word to 0.
+ /* If we're (effectively) in D3, force entire word to 0.
* This doesn't affect PME_Status, disables PME_En, and
* sets PowerState to 0.
*/
- if (dev->current_state >= PCI_D3hot) {
- if (!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
+ switch (dev->current_state) {
+ case PCI_UNKNOWN: /* Boot-up */
+ if ((pmcsr & PCI_PM_CTRL_STATE_MASK) == PCI_D3hot
+ && !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
need_restore = 1;
+ /* Fall-through: force to D0 */
+ case PCI_D3hot:
+ case PCI_D3cold:
+ case PCI_POWER_ERROR:
pmcsr = 0;
- } else {
+ break;
+ default:
pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
pmcsr |= state;
+ break;
}

/* enter specified state */