diff options
author | Ben Hutchings <bhutchings@solarflare.com> | 2010-06-17 21:16:36 +0200 |
---|---|---|
committer | Jesse Barnes <jbarnes@virtuousgeek.org> | 2010-07-30 18:29:34 +0200 |
commit | fcd097f31a6ee207cc0c3da9cccd2a86d4334785 (patch) | |
tree | 3bd2658926e691d0eab23651e45832c2714d85f6 | |
parent | PCI: Default PCIe ASPM control to on and require !EMBEDDED to disable (diff) | |
download | linux-fcd097f31a6ee207cc0c3da9cccd2a86d4334785.tar.xz linux-fcd097f31a6ee207cc0c3da9cccd2a86d4334785.zip |
PCI: MSI: Remove unsafe and unnecessary hardware access
During suspend on an SMP system, {read,write}_msi_msg_desc() may be
called to mask and unmask interrupts on a device that is already in a
reduced power state. At this point memory-mapped registers including
MSI-X tables are not accessible, and config space may not be fully
functional either.
While a device is in a reduced power state its interrupts are
effectively masked and its MSI(-X) state will be restored when it is
brought back to D0. Therefore these functions can simply read and
write msi_desc::msg for devices not in D0.
Further, read_msi_msg_desc() should only ever be used to update a
previously written message, so it can always read msi_desc::msg
and never needs to touch the hardware.
Tested-by: "Michael Chan" <mchan@broadcom.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
-rw-r--r-- | drivers/pci/msi.c | 34 |
1 files changed, 11 insertions, 23 deletions
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 6a0f2f07f955..4c14f31f2b4d 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -196,30 +196,15 @@ void unmask_msi_irq(unsigned int irq) void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg) { struct msi_desc *entry = get_irq_desc_msi(desc); - if (entry->msi_attrib.is_msix) { - void __iomem *base = entry->mask_base + - entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE; - msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR); - msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR); - msg->data = readl(base + PCI_MSIX_ENTRY_DATA); - } else { - struct pci_dev *dev = entry->dev; - int pos = entry->msi_attrib.pos; - u16 data; + /* We do not touch the hardware (which may not even be + * accessible at the moment) but return the last message + * written. Assert that this is valid, assuming that + * valid messages are not all-zeroes. */ + BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo | + entry->msg.data)); - pci_read_config_dword(dev, msi_lower_address_reg(pos), - &msg->address_lo); - if (entry->msi_attrib.is_64) { - pci_read_config_dword(dev, msi_upper_address_reg(pos), - &msg->address_hi); - pci_read_config_word(dev, msi_data_reg(pos, 1), &data); - } else { - msg->address_hi = 0; - pci_read_config_word(dev, msi_data_reg(pos, 0), &data); - } - msg->data = data; - } + *msg = entry->msg; } void read_msi_msg(unsigned int irq, struct msi_msg *msg) @@ -232,7 +217,10 @@ void read_msi_msg(unsigned int irq, struct msi_msg *msg) void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg) { struct msi_desc *entry = get_irq_desc_msi(desc); - if (entry->msi_attrib.is_msix) { + + if (entry->dev->current_state != PCI_D0) { + /* Don't touch the hardware now */ + } else if (entry->msi_attrib.is_msix) { void __iomem *base; base = entry->mask_base + entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE; |