linux-kernel - [PATCH v2 2/2] hwmon (occ): Retry for checksum failure

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Message-Id: <20220426154956.27205-3-eajames@linux.ibm.com>
Date:   Tue, 26 Apr 2022 10:49:56 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-fsi@...ts.ozlabs.org
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        jdelvare@...e.com, linux@...ck-us.net, joel@....id.au,
        jk@...abs.org, David.Laight@...LAB.COM
Subject: [PATCH v2 2/2] hwmon (occ): Retry for checksum failure

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@...ux.ibm.com>
Acked-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/hwmon/occ/p9_sbe.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
index 49b13cc01073..e6ccef2af659 100644
--- a/drivers/hwmon/occ/p9_sbe.c
+++ b/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;
@@ -83,17 +85,22 @@ static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
 	struct occ_response *resp = &occ->resp;
 	struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
 	size_t resp_len = sizeof(*resp);
+	int i;
 	int rc;
 
-	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;
 	}
 
 	switch (resp->return_status) {
-- 
2.27.0