linux-kernel - Re: [PATCH 2/3] power: supply: cpcap-battery: Fix battery identification

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Date:   Thu, 10 Nov 2022 18:50:32 +0200
From:   Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To:     Sebastian Reichel <sebastian.reichel@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony@...mide.com, philipp@...s.xyz
Subject: Re: [PATCH 2/3] power: supply: cpcap-battery: Fix battery
 identification

Hi,

On 10.11.22 г. 18:05 ч., Sebastian Reichel wrote:
> Hi,
> 
> On Sat, Nov 05, 2022 at 01:25:43PM +0200, Ivaylo Dimitrov wrote:
>> Use the same logic to identify genuine batteries as Android does.
>>
>> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
>> ---
> 
> Why do we care?
> 

Because if we know the battery is genuine (or at least pretends to be :) 
), then we can read battery parameters from nvram, see patch 3/3. This 
will allow us to charge HV LiPo batteries to 4.35V, using the full capacity.

Not to say the code currently identifies a specific battery with id of 
"89-500029ba0f73" as genuine one, ignoring all others. So this patch is 
more or less a bugfix too.

Regards,
Ivo


> -- Sebastian
> 
>>   drivers/power/supply/cpcap-battery.c | 19 ++++++++++++++-----
>>   1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/power/supply/cpcap-battery.c b/drivers/power/supply/cpcap-battery.c
>> index 8869067..ca6ee2b 100644
>> --- a/drivers/power/supply/cpcap-battery.c
>> +++ b/drivers/power/supply/cpcap-battery.c
>> @@ -422,7 +422,7 @@ static int cpcap_battery_cc_to_ua(struct cpcap_battery_ddata *ddata,
>>   
>>   static int cpcap_battery_match_nvmem(struct device *dev, const void *data)
>>   {
>> -	if (strcmp(dev_name(dev), "89-500029ba0f73") == 0)
>> +	if (strncmp(dev_name(dev), "89-500", 6) == 0)
>>   		return 1;
>>   	else
>>   		return 0;
>> @@ -439,10 +439,19 @@ static void cpcap_battery_detect_battery_type(struct cpcap_battery_ddata *ddata)
>>   	if (IS_ERR_OR_NULL(nvmem)) {
>>   		ddata->check_nvmem = true;
>>   		dev_info_once(ddata->dev, "Can not find battery nvmem device. Assuming generic lipo battery\n");
>> -	} else if (nvmem_device_read(nvmem, 2, 1, &battery_id) < 0) {
>> -		battery_id = 0;
>> -		ddata->check_nvmem = true;
>> -		dev_warn(ddata->dev, "Can not read battery nvmem device. Assuming generic lipo battery\n");
>> +	} else {
>> +		char buf[24];
>> +
>> +		if (nvmem_device_read(nvmem, 96, 4, buf) < 0 ||
>> +		    strncmp(buf, "COPR", 4) != 0 ||
>> +		    nvmem_device_read(nvmem, 104, 24, buf) < 0 ||
>> +		    strncmp(buf, "MOTOROLA E.P CHARGE ONLY", 24) != 0 ||
>> +		    nvmem_device_read(nvmem, 2, 1, &battery_id) < 0) {
>> +			battery_id = 0;
>> +			ddata->check_nvmem = true;
>> +			dev_warn(ddata->dev, "Can not read battery nvmem device. Assuming generic lipo battery\n");
>> +		}
>> +
>>   	}
>>   
>>   	switch (battery_id) {
>> -- 
>> 1.9.1
>>