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authorBjorn Helgaas <bhelgaas@google.com>2014-08-27 14:38:14 -0600
committerBjorn Helgaas <bhelgaas@google.com>2014-09-12 20:10:57 -0600
commiteab3a0ee342106a1c82e10682c02632e9d6af0df (patch)
tree517babc69f1251d4d1287048d60ae1bde726e9f1 /drivers/pci/probe.c
parentc6285fc5b55ecbf78c53301a191f04bb2fda1b3a (diff)
PCI: Preserve BIOS PCI_COMMAND_SERR and PCI_COMMAND_PARITY settings
Do not clear PCI_COMMAND_SERR or PCI_COMMAND_PARITY based on _HPP. The spec (ACPI rev 5.0, sec 6.2.7) says that when "Enable SERR" is set to 1, we should enable SERR in the command register. It says nothing about *disabling* SERR or PERR; in fact, the example in 6.2.7.1 says we should leave PERR alone unless "Enable PERR" is 1. For hot-added devices, this probably doesn't matter because they power up with these bits cleared. But in addition to hot-plugged devices, the spec allows the platform to use _HPP for "configuration of PCI devices not configured by the BIOS at system boot," and it may make a difference for devices present at boot. This change means that if BIOS enables SERR or PERR on a device, and it supplies _HPP or _HPX with the SERR or PERR bits *cleared*, we will now leave SERR or PERR reporting enabled on that device instead of disabling it as we previously did. See also 40abb96c51bb ("pciehp: Fix programming hotplug parameters"), where this code was first added. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Yinghai Lu <yinghai@kernel.org>
Diffstat (limited to 'drivers/pci/probe.c')
-rw-r--r--drivers/pci/probe.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 003d112a783d..a16b3472b70d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1264,12 +1264,8 @@ static void program_hpp_type0(struct pci_dev *dev, struct hpp_type0 *hpp)
pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);
if (hpp->enable_serr)
pci_cmd |= PCI_COMMAND_SERR;
- else
- pci_cmd &= ~PCI_COMMAND_SERR;
if (hpp->enable_perr)
pci_cmd |= PCI_COMMAND_PARITY;
- else
- pci_cmd &= ~PCI_COMMAND_PARITY;
pci_write_config_word(dev, PCI_COMMAND, pci_cmd);
/* Program bridge control value */
@@ -1279,12 +1275,8 @@ static void program_hpp_type0(struct pci_dev *dev, struct hpp_type0 *hpp)
pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &pci_bctl);
if (hpp->enable_serr)
pci_bctl |= PCI_BRIDGE_CTL_SERR;
- else
- pci_bctl &= ~PCI_BRIDGE_CTL_SERR;
if (hpp->enable_perr)
pci_bctl |= PCI_BRIDGE_CTL_PARITY;
- else
- pci_bctl &= ~PCI_BRIDGE_CTL_PARITY;
pci_write_config_word(dev, PCI_BRIDGE_CONTROL, pci_bctl);
}
}