diff mbox series

[linux,dev-5.10,02/14] pmbus: (ucd9000) Throttle SMBus transfers to avoid poor behaviour

Message ID 20210811154232.12649-3-eajames@linux.ibm.com
State New
Headers show
Series Rainier and Everest system fixes | expand

Commit Message

Eddie James Aug. 11, 2021, 3:42 p.m. UTC 
From: Andrew Jeffery <andrew@aj.id.au>

Short turn-around times between transfers to UCD9000 devices can lead to
problematic behaviour, including unnecessary clock stretching, bus
lockups and potential corruption of the device's volatile state.

Introduce transfer throttling for the device with a minimum access
delay of 1ms.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 drivers/hwmon/pmbus/ucd9000.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/drivers/hwmon/pmbus/ucd9000.c b/drivers/hwmon/pmbus/ucd9000.c
index a15e6fe3e425..9687bc3609d1 100644
--- a/drivers/hwmon/pmbus/ucd9000.c
+++ b/drivers/hwmon/pmbus/ucd9000.c
@@ -487,6 +487,8 @@  static int ucd9000_init_debugfs(struct i2c_client *client,
 }
 #endif /* CONFIG_DEBUG_FS */
 
+#define UCD9000_SMBUS_THROTTLE_US	1000
+
 static int ucd9000_probe(struct i2c_client *client)
 {
 	u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
@@ -501,6 +503,8 @@  static int ucd9000_probe(struct i2c_client *client)
 				     I2C_FUNC_SMBUS_BLOCK_DATA))
 		return -ENODEV;
 
+	i2c_smbus_throttle_client(client, UCD9000_SMBUS_THROTTLE_US);
+
 	ret = i2c_smbus_read_block_data(client, UCD9000_DEVICE_ID,
 					block_buffer);
 	if (ret < 0) {