PCI: cleanup Function Level Reset

This patch enhances the FLR functions:
  1) remove disable_irq() so the shared IRQ won't be disabled.
  2) replace the 1s wait with 100, 200 and 400ms wait intervals
     for the Pending Transaction.
  3) replace mdelay() with msleep().
  4) add might_sleep().
  5) lock the device to prevent PM suspend from accessing the CSRs
     during the reset.
  6) coding style fixes.

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 84 insertions, 82 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8ea911e55722..6a052ada3fe8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2055,111 +2055,112 @@ int pci_set_dma_seg_boundary(struct pci_dev *dev, unsigned long mask)
 EXPORT_SYMBOL(pci_set_dma_seg_boundary);
 #endif
 
-static int __pcie_flr(struct pci_dev *dev, int probe)
+static int pcie_flr(struct pci_dev *dev, int probe)
 {
-        u16 status;
+        int i;
+        int pos;
         u32 cap;
-        int exppos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+        u16 status;
 
-        if (!exppos)
+        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+        if (!pos)
                 return -ENOTTY;
-        pci_read_config_dword(dev, exppos + PCI_EXP_DEVCAP, &cap);
+
+        pci_read_config_dword(dev, pos + PCI_EXP_DEVCAP, &cap);
         if (!(cap & PCI_EXP_DEVCAP_FLR))
                 return -ENOTTY;
 
         if (probe)
                 return 0;
 
-        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;
+        for (i = 0; i < 4; i++) {
+                if (i)
+                        msleep((1 << (i - 1)) * 100);
 
-        msleep(100);
-        pci_read_config_word(dev, exppos + PCI_EXP_DEVSTA, &status);
-        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; "
-                                "proceeding with reset anyway\n");
-
-transaction_done:
-        pci_write_config_word(dev, exppos + PCI_EXP_DEVCTL,
+                pci_read_config_word(dev, pos + PCI_EXP_DEVSTA, &status);
+                if (!(status & PCI_EXP_DEVSTA_TRPND))
+                        goto clear;
+        }
+
+        dev_err(&dev->dev, "transaction is not cleared; "
+                        "proceeding with reset anyway\n");
+
+clear:
+        pci_write_config_word(dev, pos + PCI_EXP_DEVCTL,
                                 PCI_EXP_DEVCTL_BCR_FLR);
-        mdelay(100);
+        msleep(100);
 
-        pci_unblock_user_cfg_access(dev);
         return 0;
 }
 
-static int __pci_af_flr(struct pci_dev *dev, int probe)
+static int pci_af_flr(struct pci_dev *dev, int probe)
 {
-        int cappos = pci_find_capability(dev, PCI_CAP_ID_AF);
-        u8 status;
+        int i;
+        int pos;
         u8 cap;
+        u8 status;
 
-        if (!cappos)
+        pos = pci_find_capability(dev, PCI_CAP_ID_AF);
+        if (!pos)
                 return -ENOTTY;
-        pci_read_config_byte(dev, cappos + PCI_AF_CAP, &cap);
+
+        pci_read_config_byte(dev, pos + PCI_AF_CAP, &cap);
         if (!(cap & PCI_AF_CAP_TP) || !(cap & PCI_AF_CAP_FLR))
                 return -ENOTTY;
 
         if (probe)
                 return 0;
 
-        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;
+        for (i = 0; i < 4; i++) {
+                if (i)
+                        msleep((1 << (i - 1)) * 100);
+
+                pci_read_config_byte(dev, pos + PCI_AF_STATUS, &status);
+                if (!(status & PCI_AF_STATUS_TP))
+                        goto clear;
+        }
+
+        dev_err(&dev->dev, "transaction is not cleared; "
+                        "proceeding with reset anyway\n");
 
+clear:
+        pci_write_config_byte(dev, pos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);
         msleep(100);
-        pci_read_config_byte(dev, cappos + PCI_AF_STATUS, &status);
-        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);
-
-        pci_unblock_user_cfg_access(dev);
+
         return 0;
 }
 
-static int __pci_reset_function(struct pci_dev *pdev, int probe)
+static int pci_dev_reset(struct pci_dev *dev, int probe)
 {
-        int res;
+        int rc;
+
+        might_sleep();
+
+        if (!probe) {
+                pci_block_user_cfg_access(dev);
+                /* block PM suspend, driver probe, etc. */
+                down(&dev->dev.sem);
+        }
 
-        res = __pcie_flr(pdev, probe);
-        if (res != -ENOTTY)
-                return res;
+        rc = pcie_flr(dev, probe);
+        if (rc != -ENOTTY)
+                goto done;
 
-        res = __pci_af_flr(pdev, probe);
-        if (res != -ENOTTY)
-                return res;
+        rc = pci_af_flr(dev, probe);
+done:
+        if (!probe) {
+                up(&dev->dev.sem);
+                pci_unblock_user_cfg_access(dev);
+        }
 
-        return res;
+        return rc;
 }
 
 /**
- * pci_execute_reset_function() - Reset a PCI device function
- * @dev: Device function to reset
+ * __pci_reset_function - reset a PCI device function
+ * @dev: PCI device to reset
  *
  * Some devices allow an individual function to be reset without affecting
  * other functions in the same device.  The PCI device must be responsive
@@ -2171,18 +2172,18 @@ static int __pci_reset_function(struct pci_dev *pdev, int probe)
  * device including MSI, bus mastering, BARs, decoding IO and memory spaces,
  * etc.
  *
- * Returns 0 if the device function was successfully reset or -ENOTTY if the
+ * Returns 0 if the device function was successfully reset or negative if the
  * device doesn't support resetting a single function.
  */
-int pci_execute_reset_function(struct pci_dev *dev)
+int __pci_reset_function(struct pci_dev *dev)
 {
-        return __pci_reset_function(dev, 0);
+        return pci_dev_reset(dev, 0);
 }
-EXPORT_SYMBOL_GPL(pci_execute_reset_function);
+EXPORT_SYMBOL_GPL(__pci_reset_function);
 
 /**
- * pci_reset_function() - quiesce and reset a PCI device function
- * @dev: Device function to reset
+ * pci_reset_function - quiesce and reset a PCI device function
+ * @dev: PCI device to reset
  *
  * Some devices allow an individual function to be reset without affecting
  * other functions in the same device.  The PCI device must be responsive
@@ -2190,32 +2191,33 @@ EXPORT_SYMBOL_GPL(pci_execute_reset_function);
  *
  * This function does not just reset the PCI portion of a device, but
  * clears all the state associated with the device.  This function differs
- * from pci_execute_reset_function in that it saves and restores device state
+ * from __pci_reset_function in that it saves and restores device state
  * over the reset.
  *
- * Returns 0 if the device function was successfully reset or -ENOTTY if the
+ * Returns 0 if the device function was successfully reset or negative if the
  * device doesn't support resetting a single function.
  */
 int pci_reset_function(struct pci_dev *dev)
 {
-        int r = __pci_reset_function(dev, 1);
+        int rc;
 
-        if (r < 0)
-                return r;
+        rc = pci_dev_reset(dev, 1);
+        if (rc)
+                return rc;
 
-        if (!dev->msi_enabled && !dev->msix_enabled && dev->irq != 0)
-                disable_irq(dev->irq);
         pci_save_state(dev);
 
+        /*
+         * both INTx and MSI are disabled after the Interrupt Disable bit
+         * is set and the Bus Master bit is cleared.
+         */
         pci_write_config_word(dev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
 
-        r = pci_execute_reset_function(dev);
+        rc = pci_dev_reset(dev, 0);
 
         pci_restore_state(dev);
-        if (!dev->msi_enabled && !dev->msix_enabled && dev->irq != 0)
-                enable_irq(dev->irq);
 
-        return r;
+        return rc;
 }
 EXPORT_SYMBOL_GPL(pci_reset_function);