linux-kernel - [PATCH] fsi: i2cr: Reduce status checks for read operations

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Date: Tue, 23 Apr 2024 11:18:02 -0500
From: Eddie James <eajames@...ux.ibm.com>
To: linux-fsi@...ts.ozlabs.org
Cc: linux-kernel@...r.kernel.org, joel@....id.au, jk@...abs.org,
        alistair@...ple.id.au, Eddie James <eajames@...ux.ibm.com>
Subject: [PATCH] fsi: i2cr: Reduce status checks for read operations

As an optimization, only check the status register if the eight
byte i2c read operation returns 0xffffffffffffffff. This indicates
that the I2C Responder operation failed and the status register
will provide the reason. Otherwise, the operation was successful,
so no status check is necessary.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/fsi/fsi-master-i2cr.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/fsi/fsi-master-i2cr.c b/drivers/fsi/fsi-master-i2cr.c
index 40f1f4d231e5..9bb5c008995e 100644
--- a/drivers/fsi/fsi-master-i2cr.c
+++ b/drivers/fsi/fsi-master-i2cr.c
@@ -145,9 +145,11 @@ int fsi_master_i2cr_read(struct fsi_master_i2cr *i2cr, u32 addr, u64 *data)
 	if (ret)
 		goto unlock;
 
-	ret = i2cr_check_status(i2cr->client);
-	if (ret)
-		goto unlock;
+	if (*data == 0xffffffffffffffffull) {
+		ret = i2cr_check_status(i2cr->client);
+		if (ret)
+			goto unlock;
+	}
 
 	trace_i2cr_read(i2cr->client, command, data);
 
-- 
2.39.3