linux-kernel - [PATCH v1] hwmon: (ucd90320) Increase delay from 250 to 500us

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Date: Tue,  7 May 2024 14:46:03 -0500
From: Lakshmi Yadlapati <lakshmiy@...ibm.com>
To: jdelvare@...e.com, linux@...ck-us.net
Cc: Lakshmi Yadlapati <lakshmiy@...ibm.com>, ninad@...ux.ibm.com,
        eajames@...ux.ibm.com, linux-kernel@...r.kernel.org
Subject: [PATCH v1] hwmon: (ucd90320) Increase delay from 250 to 500us

Following the failure observed with a delay of 250us, experiments were
conducted with various delays. It was found that a delay of 350us
effectively mitigated the issue.

To provide a more optimal solution while still allowing a margin for
stability, the delay is being adjusted to 500us.

Signed-off-by: Lakshmi Yadlapati <lakshmiy@...ibm.com>
---
 drivers/hwmon/pmbus/ucd9000.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pmbus/ucd9000.c b/drivers/hwmon/pmbus/ucd9000.c
index 8d9d422450e5..d817c719b90b 100644
--- a/drivers/hwmon/pmbus/ucd9000.c
+++ b/drivers/hwmon/pmbus/ucd9000.c
@@ -80,11 +80,11 @@ struct ucd9000_debugfs_entry {
  * It has been observed that the UCD90320 randomly fails register access when
  * doing another access right on the back of a register write. To mitigate this
  * make sure that there is a minimum delay between a write access and the
- * following access. The 250us is based on experimental data. At a delay of
- * 200us the issue seems to go away. Add a bit of extra margin to allow for
+ * following access. The 500 is based on experimental data. At a delay of
+ * 350us the issue seems to go away. Add a bit of extra margin to allow for
  * system to system differences.
  */
-#define UCD90320_WAIT_DELAY_US 250
+#define UCD90320_WAIT_DELAY_US 500
 
 static inline void ucd90320_wait(const struct ucd9000_data *data)
 {
-- 
2.40.1