[PATCH 4.19 56/86] hwmon: (adm1275) Make sure we are reading enough data for different chips

Greg Kroah-Hartman
2020-07-27T14:11:18Z

From: Chu Lin <linchuyuan@google.com>

[ Upstream commit 6d1d41c075a1a54ba03370e268171fec20e06563 ]

Issue:
When PEC is enabled, binding adm1272 to the adm1275 would
fail due to PEC error. See below:
adm1275: probe of xxxx failed with error -74

Diagnosis:
Per the datasheet of adm1272, adm1278, adm1293 and amd1294,
PMON_CONFIG (0xd4) is 16bits wide. On the other hand,
PMON_CONFIG (0xd4) for adm1275 is 8bits wide. The driver should not
assume everything is 8bits wide and read only 8bits from it.

Solution:
If it is adm1272, adm1278, adm1293 and adm1294, use i2c_read_word.
Else, use i2c_read_byte

Testing:
Binding adm1272 to the driver.
The change is only tested on adm1272.

Signed-off-by: Chu Lin <linchuyuan@google.com>
Link: https://lore.kernel.org/r/20200709040612.3977094-1-linchuyuan@google.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/pmbus/adm1275.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
index 13600fa79e7f3..a19cf9052fc6d 100644
--- a/drivers/hwmon/pmbus/adm1275.c
+++ b/drivers/hwmon/pmbus/adm1275.c
@@ -364,6 +364,7 @@ MODULE_DEVICE_TABLE(i2c, adm1275_id);
static int adm1275_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
+ s32 (*config_read_fn)(const struct i2c_client *client, u8 reg);
u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
int config, device_config;
int ret;
@@ -408,11 +409,16 @@ static int adm1275_probe(struct i2c_client *client,
"Device mismatch: Configured %s, detected %s\n",
id->name, mid->name);

- config = i2c_smbus_read_byte_data(client, ADM1275_PMON_CONFIG);
+ if (mid->driver_data == adm1272 || mid->driver_data == adm1278 ||
+ mid->driver_data == adm1293 || mid->driver_data == adm1294)
+ config_read_fn = i2c_smbus_read_word_data;
+ else
+ config_read_fn = i2c_smbus_read_byte_data;
+ config = config_read_fn(client, ADM1275_PMON_CONFIG);
if (config < 0)
return config;

- device_config = i2c_smbus_read_byte_data(client, ADM1275_DEVICE_CONFIG);
+ device_config = config_read_fn(client, ADM1275_DEVICE_CONFIG);
if (device_config < 0)
return device_config;

--
2.25.1