Commit 97c145f7 authored Nov 05, 2010 by Jesse Barnes

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 <jesse.brandeburg@gmail.com>
Reported-by: Dave Airlie <airlied@linux.ie>
Tested-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

parent 3b519e4e

drivers/pci/pci.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -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 */