2020-12-22 15:29:35

by Eddie James

Subject: [PATCH v2 1/2] hwmon: (pmbus) Add a PMBUS_NO_CAPABILITY platform data flag

Some PMBus chips don't respond with valid data when reading the
CAPABILITY register. Add a flag that device drivers can set so
that the PMBus core driver doesn't use CAPABILITY to determine it's
behavior.

Signed-off-by: Eddie James <[email protected]>
---
drivers/hwmon/pmbus/pmbus_core.c | 8 +++++---
include/linux/pmbus.h | 9 +++++++++
2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 192442b3b7a2..906c9fec9cce 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2204,9 +2204,11 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
}

/* Enable PEC if the controller supports it */
- ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
- if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
- client->flags |= I2C_CLIENT_PEC;
+ if (!(data->flags & PMBUS_NO_CAPABILITY)) {
+ ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
+ if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
+ client->flags |= I2C_CLIENT_PEC;
+ }

/*
* Check if the chip is write protected. If it is, we can not clear
diff --git a/include/linux/pmbus.h b/include/linux/pmbus.h
index 1ea5bae708a1..12cbbf305969 100644
--- a/include/linux/pmbus.h
+++ b/include/linux/pmbus.h
@@ -34,6 +34,15 @@
*/
#define PMBUS_WRITE_PROTECTED BIT(1)

+/*
+ * PMBUS_NO_CAPABILITY
+ *
+ * Some PMBus chips don't respond with valid data when reading the CAPABILITY
+ * register. For such chips, this flag should be set so that the PMBus core
+ * driver doesn't use CAPABILITY to determine it's behavior.
+ */
+#define PMBUS_NO_CAPABILITY BIT(2)
+
struct pmbus_platform_data {
u32 flags; /* Device specific flags */

--
2.27.0

2020-12-23 15:45:35

by Guenter Roeck

Subject: Re: [PATCH v2 1/2] hwmon: (pmbus) Add a PMBUS_NO_CAPABILITY platform data flag

On Tue, Dec 22, 2020 at 09:26:39AM -0600, Eddie James wrote:
> Some PMBus chips don't respond with valid data when reading the
> CAPABILITY register. Add a flag that device drivers can set so
> that the PMBus core driver doesn't use CAPABILITY to determine it's
> behavior.
>
> Signed-off-by: Eddie James <[email protected]>

Applied.

Thanks,
Guenter