hwmon (occ): Retry for checksum failure

[ Upstream commit dbed963 ]

Due to the OCC communication design with a shared SRAM area,
checkum errors are expected due to corrupted buffer from OCC
communications with other system components. Therefore, retry
the command twice in the event of a checksum failure.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220426154956.27205-3-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/hwmon/occ/p9_sbe.c

@@ -14,6 +14,8 @@
 
 #include "common.h"
 
+#define OCC_CHECKSUM_RETRIES	3
+
 struct p9_sbe_occ {
 	struct occ occ;
 	bool sbe_error;
@@ -80,18 +82,23 @@ static bool p9_sbe_occ_save_ffdc(struct p9_sbe_occ *ctx, const void *resp,
 static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len,
 			       void *resp, size_t resp_len)
 {
+	size_t original_resp_len = resp_len;
 	struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
-	int rc;
+	int rc, i;
 
-	rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
-	if (rc < 0) {
+	for (i = 0; i < OCC_CHECKSUM_RETRIES; ++i) {
+		rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
+		if (rc >= 0)
+			break;
 		if (resp_len) {
 			if (p9_sbe_occ_save_ffdc(ctx, resp, resp_len))
 				sysfs_notify(&occ->bus_dev->kobj, NULL,
 					     bin_attr_ffdc.attr.name);
+			return rc;
 		}
-
-		return rc;
+		if (rc != -EBADE)
+			return rc;
+		resp_len = original_resp_len;
 	}
 
 	switch (((struct occ_response *)resp)->return_status) {