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path: root/drivers/pci/pci.c
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-rw-r--r--drivers/pci/pci.c65
1 files changed, 48 insertions, 17 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index af0cc3456dc1..827a9f99a8e5 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -52,6 +52,7 @@ static void pci_pme_list_scan(struct work_struct *work);
static LIST_HEAD(pci_pme_list);
static DEFINE_MUTEX(pci_pme_list_mutex);
static DECLARE_DELAYED_WORK(pci_pme_work, pci_pme_list_scan);
+static DEFINE_MUTEX(pci_bridge_mutex);
struct pci_pme_device {
struct list_head list;
@@ -1348,10 +1349,16 @@ static void pci_enable_bridge(struct pci_dev *dev)
if (bridge)
pci_enable_bridge(bridge);
+ /*
+ * Hold pci_bridge_mutex to prevent a race when enabling two
+ * devices below the bridge simultaneously. The race may cause a
+ * PCI_COMMAND_MEMORY update to be lost (see changelog).
+ */
+ mutex_lock(&pci_bridge_mutex);
if (pci_is_enabled(dev)) {
if (!dev->is_busmaster)
pci_set_master(dev);
- return;
+ goto end;
}
retval = pci_enable_device(dev);
@@ -1359,6 +1366,8 @@ static void pci_enable_bridge(struct pci_dev *dev)
dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n",
retval);
pci_set_master(dev);
+end:
+ mutex_unlock(&pci_bridge_mutex);
}
static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
@@ -1383,7 +1392,7 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
return 0; /* already enabled */
bridge = pci_upstream_bridge(dev);
- if (bridge)
+ if (bridge && !pci_is_enabled(bridge))
pci_enable_bridge(bridge);
/* only skip sriov related */
@@ -3811,27 +3820,49 @@ 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. We read the 2nd
- * dword because VFs don't implement the 1st dword.
- */
static void pci_flr_wait(struct pci_dev *dev)
{
- int i = 0;
+ int delay = 1, timeout = 60000;
u32 id;
- do {
- msleep(100);
+ /*
+ * Per PCIe r3.1, sec 6.6.2, a device must complete an FLR within
+ * 100ms, but may silently discard requests while the FLR is in
+ * progress. Wait 100ms before trying to access the device.
+ */
+ msleep(100);
+
+ /*
+ * After 100ms, the device should not silently discard config
+ * requests, but it may still indicate that it needs more time by
+ * responding to them with CRS completions. The Root Port will
+ * generally synthesize ~0 data to complete the read (except when
+ * CRS SV is enabled and the read was for the Vendor ID; in that
+ * case it synthesizes 0x0001 data).
+ *
+ * Wait for the device to return a non-CRS completion. Read the
+ * Command register instead of Vendor ID so we don't have to
+ * contend with the CRS SV value.
+ */
+ pci_read_config_dword(dev, PCI_COMMAND, &id);
+ while (id == ~0) {
+ if (delay > timeout) {
+ dev_warn(&dev->dev, "not ready %dms after FLR; giving up\n",
+ 100 + delay - 1);
+ return;
+ }
+
+ if (delay > 1000)
+ dev_info(&dev->dev, "not ready %dms after FLR; waiting\n",
+ 100 + delay - 1);
+
+ msleep(delay);
+ delay *= 2;
pci_read_config_dword(dev, PCI_COMMAND, &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);
+ if (delay > 1000)
+ dev_info(&dev->dev, "ready %dms after FLR\n", 100 + delay - 1);
}
/**