bnx2: Try to recover from PCI block reset

If the PCI block has reset, the memory enable bit will be reset and
the device will not respond to MMIO access. bnx2_reset_task() currently
will not recover when this happens. Add code to detect this condition
and restore the PCI state. This scenario has been reported by some
users.

Signed-off-by: Michael Chan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/bnx2.c

···
 {
 	struct bnx2 *bp = container_of(work, struct bnx2, reset_task);
 	int rc;
+	u16 pcicmd;
 
 	rtnl_lock();
 	if (!netif_running(bp->dev)) {
···
 
 	bnx2_netif_stop(bp, true);
 
+	pci_read_config_word(bp->pdev, PCI_COMMAND, &pcicmd);
+	if (!(pcicmd & PCI_COMMAND_MEMORY)) {
+		/* in case PCI block has reset */
+		pci_restore_state(bp->pdev);
+		pci_save_state(bp->pdev);
+	}
 	rc = bnx2_init_nic(bp, 1);
 	if (rc) {
 		netdev_err(bp->dev, "failed to reset NIC, closing\n");