6.6-stable review patch. If anyone has any objections, please let me know.
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From: Lakshmi Yadlapati lakshmiy@us.ibm.com
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@us.ibm.com Link: https://lore.kernel.org/r/20240507194603.1305750-1-lakshmiy@us.ibm.com Fixes: 8d655e6523764 ("hwmon: (ucd90320) Add minimum delay between bus accesses") Reviewed-by: Eddie James eajames@linux.ibm.com Cc: stable@vger.kernel.org Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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) {