On Tue, 16 Feb 2016 13:53:19 -0700 Alex Williamson <[email protected]> wrote:
> Some devices take longer than the spec indicates to return from FLR > reset, a notable case of this is Intel integrated graphics (IGD), > which can often take an additional 300ms powering down an attached > LCD panel as part of the FLR. Allow devices up to 1000ms, testing > every 100ms whether the first dword of config space is read as -1. > > Signed-off-by: Alex Williamson <[email protected]> > --- Self nak on this one, didn't account for VFs not implementing the first dword. Thanks, Alex > v2: Change loop to incorporate initial 100ms delay, replace delay in > callee functions, add comment. > > drivers/pci/pci.c | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 602eb42..0ce153c 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3414,6 +3414,28 @@ int pci_wait_for_pending_transaction(struct pci_dev > *dev) > } > EXPORT_SYMBOL(pci_wait_for_pending_transaction); > > +/* > + * We should only need to wait 100ms after FLR, but some devices take longer. > + * Wait for up to 1000ms for config space to return something other than -1. > + * Intel IGD requires this when an LCD panel is attached. > + */ > +static void pci_flr_wait(struct pci_dev *dev) > +{ > + int i = 0; > + u32 id; > + > + do { > + msleep(100); > + pci_read_config_dword(dev, PCI_VENDOR_ID, &id); > + } while (i++ < 10 && id == ~0); > + > + if (id == ~0) > + dev_warn(&dev->dev, "Failed to return from FLR\n"); > + else if (i > 1) > + dev_info(&dev->dev, "Required additional " > + "%dms to return from FLR\n", (i - 1) * 100); > +} > + > static int pcie_flr(struct pci_dev *dev, int probe) > { > u32 cap; > @@ -3429,7 +3451,7 @@ static int pcie_flr(struct pci_dev *dev, int probe) > dev_err(&dev->dev, "timed out waiting for pending transaction; > performing function level reset anyway\n"); > > pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR); > - msleep(100); > + pci_flr_wait(dev); > return 0; > } > > @@ -3459,7 +3481,7 @@ static int pci_af_flr(struct pci_dev *dev, int probe) > dev_err(&dev->dev, "timed out waiting for pending transaction; > performing AF function level reset anyway\n"); > > pci_write_config_byte(dev, pos + PCI_AF_CTRL, PCI_AF_CTRL_FLR); > - msleep(100); > + pci_flr_wait(dev); > return 0; > } > >
