Date:   Tue, 17 Jan 2017 15:47:38 +1100
From:   Chris Lapa <chris@...a.com.au>
To:     "Andrew F. Davis" <afd@...com>,
        Pali Rohár <pali.rohar@...il.com>
Cc:     Sebastian Reichel <sre@...nel.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: BQ27xxx registers

On 17/1/17 4:43 am, Andrew F. Davis wrote:
> On 12/21/2016 05:37 PM, Chris Lapa wrote:
>> On 21/12/16 11:46 pm, Pali Rohár wrote:
>>> On Wednesday 21 December 2016 03:49:10 Chris Lapa wrote:
>>>> On 20/12/16 10:34 pm, Pali Rohár wrote:
>>>>> On Tuesday 20 December 2016 07:00:41 Chris Lapa wrote:
>>>>>> I can generate a patch to fix this issue, however the bigger
>>>>>> problem exists as to which revision fuel gauge the
>>>>>> bq27xxx_battery.c driver is intended to support for each family.
>>>>>
>>>>> Hi! I think driver should support all revisions. There can be (and
>>>>> probably really is) hardware which uses old revision and such
>>>>> hardware should be still supported...
>>>>
>>>> I agree. However due to the register address changes across the
>>>> spectrum of revisions, each revision will have to be specified
>>>> individually. For example, we will need to implement a BQ27510G1,
>>>> BQ27510G2, BQ27510G3, BQ27520G1, BQ27520G2, BQ27520G3, BQ27520G4
>>>> definitions and prospective device tree additions ti,bq27510g1,
>>>> ti,bq27510g2 etc.
>>>>
>>>> The other option is to aim for bottom of the barrel support for all
>>>> the devices under the BQ27500 definition but my feeling is it would
>>>> get messier fast and be less maintainable.
>>>>
>>>> My preference is to go with the first option if you agree?
>>>
>>> Yes. If those chips have different register addresses, then those chips
>>> are different. Name, generation or suffix does not matter here.
>>>
>>> Similarly there could be chips with different name, but same addresses,
>>> so can use one driver/configuration without any change.
>>>
>>> So I'm for different name in device tree (or platform data or what is
>>> being used) to distinguish between different revisions.
>>>
>>
>> I've been working my way through the revision migration datasheets and
>> noticed this could be simplified with the FW_VERSION parameter. It is
>> always located at the same address and is distinctly different between
>> each chip revision. Unfortunately the migration datasheets vs individual
>> revision datasheets firmware version information directly contradict
>> each other. Which makes me wary of committing to using it.
>>
>
> BTW, could you give some specific examples of this? I can work with the
> HW teams to get any documentation problems fixed, so we can in the
> future use this FW_VERSION parameter if needed.
>
> Thanks,
> Andrew
>
>> Given that I don't have every single variant of this device to test
>> with, its probably still safest to have the user manually specify each
>> device. I should have some patches ready soon.
>>
>> Thanks,
>> Chris
>>

Hi Andrew,

I've gone through and made a table based on the migration datasheets and
user manuals TI has provided.

CHIP		Migration D/S	User Manual
BQ27500/1 	N/A		1.06, 1.08
BQ27500-V100	1.08		1.06, 1.08
BQ27500-V120	1.20		1.20
BQ27500-V130	1.30		1.30
BQ27510-G1	1.12		Not listed
BQ27510-G2	1.23		Not listed
BQ27510-G3	4.00		4.00
BQ27520-G1	3.02 		3.01
BQ27520-G2	3.11		3.11
BQ27520-G3	3.24		3.23
BQ27520-G4	3.29		3.29

I suspect the BQ27500/1 and BQ27500-V100 are the same product but they
have separate product pages so I treated them separately. I also suspect
the different firmware revisions are probably legitimate due bugs being
fixed between when the user manual was released vs when the migration
datasheet was released.

Using the FW_VERSION parameter would be ideal, but some quick googling 
on golden images indicates that they include firmware. Which might 
introduce some more firmware variants?

Thanks,
Chris

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