This is a note to let you know that I've just added the patch titled
hwmon: (pmbus/ucd9000) Increase delay from 250 to 500us
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hwmon-pmbus-ucd9000-increase-delay-from-250-to-500us.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 26e8383b116d0dbe74e28f86646563ab46d66d83 Mon Sep 17 00:00:00 2001
From: Lakshmi Yadlapati <lakshmiy@xxxxxxxxxx>
Date: Tue, 7 May 2024 14:46:03 -0500
Subject: hwmon: (pmbus/ucd9000) Increase delay from 250 to 500us
From: Lakshmi Yadlapati <lakshmiy@xxxxxxxxxx>
commit 26e8383b116d0dbe74e28f86646563ab46d66d83 upstream.
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@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240507194603.1305750-1-lakshmiy@xxxxxxxxxx
Fixes: 8d655e6523764 ("hwmon: (ucd90320) Add minimum delay between bus accesses")
Reviewed-by: Eddie James <eajames@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hwmon/pmbus/ucd9000.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- 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)
{
Patches currently in stable-queue which might be from lakshmiy@xxxxxxxxxx are
queue-6.6/hwmon-pmbus-ucd9000-increase-delay-from-250-to-500us.patch
