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authorBen Hutchings <bhutchings@solarflare.com>2010-06-17 20:16:36 +0100
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-07-30 09:29:34 -0700
commitfcd097f31a6ee207cc0c3da9cccd2a86d4334785 (patch)
tree3bd2658926e691d0eab23651e45832c2714d85f6 /drivers/pci
parentea5f9fc5899660dd26c1ccf3fab183bd041140ee (diff)
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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>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/msi.c34
1 files changed, 11 insertions, 23 deletions
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 6a0f2f0..4c14f31 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;
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