cciss: disable doorbell reset on reset_devices

The doorbell reset initially appears to work correctly,
the controller resets, comes up, some i/o can even be
done, but on at least some Smart Arrays in some servers,
it eventually causes a subsequent controller lockup due
to some kind of PCIe error, and kdump can end up leaving
the root filesystem in an unbootable state.  For this
reason, until the problem is fixed, or at least isolated
to certain hardware enough to be avoided, the doorbell
reset should not be used at all.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/block/cciss.c

@@ -4519,6 +4519,12 @@ static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 	misc_fw_support = readl(&cfgtable->misc_fw_support);
 	use_doorbell = misc_fw_support & MISC_FW_DOORBELL_RESET;
 
+	/* The doorbell reset seems to cause lockups on some Smart
+	 * Arrays (e.g. P410, P410i, maybe others).  Until this is
+	 * fixed or at least isolated, avoid the doorbell reset.
+	 */
+	use_doorbell = 0;
+
 	rc = cciss_controller_hard_reset(pdev, vaddr, use_doorbell);
 	if (rc)
 		goto unmap_cfgtable;