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SubjectRe: [PATCH] hwmon: (pmbus_core) Check adapter PEC support
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Dear Guenter,


Am 05.06.21 um 02:51 schrieb Guenter Roeck:
> On Fri, Jun 04, 2021 at 03:57:14PM +0200, Paul Menzel wrote:
>> From: Madhava Reddy Siddareddygari <msiddare@cisco.com>
>>
>> Currently, for Packet Error Checking (PEC) only the controller
>> is checked for support. This causes problems on the cisco-8000
>> platform where a SMBUS transaction errors are observed. This is
>> because PEC has to be enabled only if both controller and
>> adapter support it.
>>
>> Added code to check PEC capability for adapter and enable it
>> only if both controller and adapter supports PEC.
>>
>> Signed-off-by: Madhava Reddy Siddareddygari <msiddare@cisco.com>
>> [Upstream from SONiC https://github.com/Azure/sonic-linux-kernel/pull/215]
>> Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
>> ---
>> drivers/hwmon/pmbus/pmbus_core.c | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>> index bbd745178147..7fbd82b7560d 100644
>> --- a/drivers/hwmon/pmbus/pmbus_core.c
>> +++ b/drivers/hwmon/pmbus/pmbus_core.c
>> @@ -2214,11 +2214,13 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
>> data->has_status_word = true;
>> }
>>
>> - /* Enable PEC if the controller supports it */
>> - if (!(data->flags & PMBUS_NO_CAPABILITY)) {
>
> What is the rationale for removing this check ?
> AFAICS that will render the ibm-cffps driver unusable.

I screwed up forward porting this change. Thank you for spotting this. I
sent a second iteration/version 2 of this patch.


Kind regards,

Paul


>> - ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
>> - if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK))
>> + /* Enable PEC if the controller and bus supports it */
>> + ret = i2c_smbus_read_byte_data(client, PMBUS_CAPABILITY);
>> + if (ret >= 0 && (ret & PB_CAPABILITY_ERROR_CHECK)) {
>> + if (i2c_check_functionality(client->adapter,
>> + I2C_FUNC_SMBUS_PEC)) {
>> client->flags |= I2C_CLIENT_PEC;
>> + }
>> }
>>
>> /*
>> --
>> 2.32.0.rc2

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