From 97c145f7c87453cec90e91238fba5fe2c1561b32 Mon Sep 17 00:00:00 2001 From: Jesse Barnes Date: Fri, 5 Nov 2010 15:16:36 -0400 Subject: [PATCH] PCI: read current power state at enable time When we enable a PCI device, we avoid doing a lot of the initial setup work if the device's enable count is non-zero. If we don't fetch the power state though, we may later fail to set up MSI due to the unknown status. So pick it up before we short circuit the rest due to a pre-existing enable or mismatched enable/disable pair (as happens with VGA devices, which are special in a special way). Tested-by: Jesse Brandeburg Reported-by: Dave Airlie Tested-by: Dave Airlie Signed-off-by: Jesse Barnes --- drivers/pci/pci.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e98c8104297b..710c8a29be0d 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1007,6 +1007,18 @@ static int __pci_enable_device_flags(struct pci_dev *dev, int err; int i, bars = 0; + /* + * Power state could be unknown at this point, either due to a fresh + * boot or a device removal call. So get the current power state + * so that things like MSI message writing will behave as expected + * (e.g. if the device really is in D0 at enable time). + */ + if (dev->pm_cap) { + u16 pmcsr; + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); + dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); + } + if (atomic_add_return(1, &dev->enable_cnt) > 1) return 0; /* already enabled */ -- 2.20.1