Re: [PATCH] surface: surface3_power: Fix battery readings on batteries with a serial no

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 2/24/22 11:55, Benjamin Tissoires wrote:
> On Thu, Feb 24, 2022 at 11:19 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> The battery on the 2nd hand Surface 3 which I recently bought appears to
>> not have a serial no programmed in. This results in any I2C reads from
>> the registers containing the serial no failing with an I2C NACK.
>>
>> This was causing mshw0011_bix() to fail causing the battery readings to
>> not work at all.
>>
>> Ignore EREMOTEIO (I2C NACK) errors when retrieving the serial no and
>> continue with an empty serial no to fix this.
>>
>> Fixes: b1f81b496b0d ("platform/x86: surface3_power: MSHW0011 rev-eng implementation")
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> 
> LGTM, (and scratching this off my list):

Ah, so I guess this was already a known issue also hit by others ?

Do you have a buglink which I can add to the commit message ?


> Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Thanks.

Regards,

Hans


>> ---
>>  drivers/platform/surface/surface3_power.c | 13 ++++++++++---
>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/platform/surface/surface3_power.c b/drivers/platform/surface/surface3_power.c
>> index abac3eec565e..b283bc9bb5fd 100644
>> --- a/drivers/platform/surface/surface3_power.c
>> +++ b/drivers/platform/surface/surface3_power.c
>> @@ -232,14 +232,21 @@ static int mshw0011_bix(struct mshw0011_data *cdata, struct bix *bix)
>>         }
>>         bix->last_full_charg_capacity = ret;
>>
>> -       /* get serial number */
>> +       /*
>> +        * get serial number, on some devices (with unofficial replacement
>> +        * battery?) reading any of the serial no range addresses gets nacked
>> +        * in this case just leave the serial no empty.
>> +        */
>>         ret = i2c_smbus_read_i2c_block_data(client, MSHW0011_BAT0_REG_SERIAL_NO,
>>                                             sizeof(buf), buf);
>> -       if (ret != sizeof(buf)) {
>> +       if (ret == -EREMOTEIO) {
>> +               /* no serial number available */
>> +       } else if (ret != sizeof(buf)) {
>>                 dev_err(&client->dev, "Error reading serial no: %d\n", ret);
>>                 return ret;
>> +       } else {
>> +               snprintf(bix->serial, ARRAY_SIZE(bix->serial), "%3pE%6pE", buf + 7, buf);
>>         }
>> -       snprintf(bix->serial, ARRAY_SIZE(bix->serial), "%3pE%6pE", buf + 7, buf);
>>
>>         /* get cycle count */
>>         ret = i2c_smbus_read_word_data(client, MSHW0011_BAT0_REG_CYCLE_CNT);
>> --
>> 2.35.1
>>
>