[PATCH 4/8] rsxx: Adding EEH check inside cregs timeout.

["Philip J. Kelleher" <pjk1939@linux.vnet.ibm.com>]

From: Philip J Kelleher <pjk1939@linux.vnet.ibm.com>

Unfortunaly, our CPU register path does not do any kind of
EEH error checking. So to fix this issue, an ioread32 was
added to the CPU register timeout code. This way, the
driver can check to see if the timeout was caused by an EEH
error or not. This is a dummy read.

Signed-off-by: Philip J Kelleher <pjk1939@linux.vnet.ibm.com>
-------------------------------------------------------------------------------


diff -uprN -X linux-block/Documentation/dontdiff linux-block-vanilla/drivers/block/rsxx/cregs.c linux-block/drivers/block/rsxx/cregs.c
--- linux-block-vanilla/drivers/block/rsxx/cregs.c	2013-05-31 15:37:27.481079110 -0500
+++ linux-block/drivers/block/rsxx/cregs.c	2013-05-31 16:35:52.306080966 -0500
@@ -431,6 +431,15 @@ static int __issue_creg_rw(struct rsxx_c
 	*hw_stat = completion.creg_status;
 
 	if (completion.st) {
+		/*
+		 * This read is needed to verify that there has not been any
+		 * extreme errors that might have occurred, i.e. EEH. The
+		 * function iowrite32 will not detect EEH errors, so it is
+		 * necessary that we recover if such an error is the reason
+		 * for the timeout. This is a dummy read.
+		 */
+		ioread32(card->regmap + SCRATCH);
+
 		dev_warn(CARD_TO_DEV(card),
 			"creg command failed(%d x%08x)\n",
 			completion.st, addr);