PCI: Speed up device reset function

For all devices need to do function level reset, currently we need wait for
at least 200ms, which can be too long if we have lots of devices...

The patch checked pending bit before msleep() to skip some unnecessary
sleeping interval.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 29 insertions, 17 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5737b8a9a732..0b3e20f1b6f7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2028,18 +2028,24 @@ static int __pcie_flr(struct pci_dev *dev, int probe)
         pci_block_user_cfg_access(dev);
 
         /* Wait for Transaction Pending bit clean */
+        pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
+        if (!(status & PCI_EXP_DEVSTA_TRPND))
+                goto transaction_done;
+
         msleep(100);
         pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
-        if (status & PCI_EXP_DEVSTA_TRPND) {
-                dev_info(&dev->dev, "Busy after 100ms while trying to reset; "
+        if (!(status & PCI_EXP_DEVSTA_TRPND))
+                goto transaction_done;
+
+        dev_info(&dev->dev, "Busy after 100ms while trying to reset; "
                         "sleeping for 1 second\n");
-                ssleep(1);
-                pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
-                if (status & PCI_EXP_DEVSTA_TRPND)
-                        dev_info(&dev->dev, "Still busy after 1s; "
+        ssleep(1);
+        pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
+        if (status & PCI_EXP_DEVSTA_TRPND)
+                dev_info(&dev->dev, "Still busy after 1s; "
                                 "proceeding with reset anyway\n");
-        }
 
+transaction_done:
         pci_write_config_word(dev, exppos + PCI_EXP_DEVCTL,
                                 PCI_EXP_DEVCTL_BCR_FLR);
         mdelay(100);
@@ -2066,18 +2072,24 @@ static int __pci_af_flr(struct pci_dev *dev, int probe)
         pci_block_user_cfg_access(dev);
 
         /* Wait for Transaction Pending bit clean */
+        pci_read_config_byte(dev, cappos + PCI_AF_STATUS, &status);
+        if (!(status & PCI_AF_STATUS_TP))
+                goto transaction_done;
+
         msleep(100);
         pci_read_config_byte(dev, cappos + PCI_AF_STATUS, &status);
-        if (status & PCI_AF_STATUS_TP) {
-                dev_info(&dev->dev, "Busy after 100ms while trying to"
-                                " reset; sleeping for 1 second\n");
-                ssleep(1);
-                pci_read_config_byte(dev,
-                                cappos + PCI_AF_STATUS, &status);
-                if (status & PCI_AF_STATUS_TP)
-                        dev_info(&dev->dev, "Still busy after 1s; "
-                                        "proceeding with reset anyway\n");
-        }
+        if (!(status & PCI_AF_STATUS_TP))
+                goto transaction_done;
+
+        dev_info(&dev->dev, "Busy after 100ms while trying to"
+                        " reset; sleeping for 1 second\n");
+        ssleep(1);
+        pci_read_config_byte(dev, cappos + PCI_AF_STATUS, &status);
+        if (status & PCI_AF_STATUS_TP)
+                dev_info(&dev->dev, "Still busy after 1s; "
+                                "proceeding with reset anyway\n");
+
+transaction_done:
         pci_write_config_byte(dev, cappos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);
         mdelay(100);