Re: Should 9aafabc7fece be reverted?

["Andrew F. Davis" <afd@ti.com>]

On 05/20/2016 05:35 AM, Pali Rohár wrote:
> On Friday 20 May 2016 11:34:32 Pavel Machek wrote:
>> Hi!
>>
>>>> I think it is insane to starts generating random numbers for IDR... Hard 
>>>> to decide what happen if such situation occur...
>>>>
>>>
>>> That's kind of what I'm looking for though, if the userspace break is
>>> caused by software relying on the battery to be named "bq27200-0", then
>>> nothing short of hard-coding this exact name will 100% safely fix the
>>> N900 userspace software. And so using IDR and hoping it gives 0 is just
>>> a hacky work-around way of just naming the device "bq27200-0".
>>
>> BTW proposals how to fix that userspace would be welcome.
>>
>> We have three "power supplies", but userspace does not know how they
>> are connecting, resulting in strange results. For now, I have
>> hardware-specific layer in userspace.
>>
>> https://gitlab.com/tui/tui/blob/master/ofone/hardware.py
>>
>> Kernel does not really give me other choice.
> 
> I have in my mind idea of "merged" power supply devices.
> 
> For Nokia N900 we have:
> * bq27200 monitoring chip
> * bq24150a charging chip
> * isp1707 usb phy chargin chip (wallcharger detection + enable gpio)
> * rx51_battery driver (export ADC values from battery pins: temperature + design capacity)
> 
> And each part export own power supply device in /sys/class/power_supply/
> So there are 4 power supply devices!
> 
> In ideal world kernel should provide into userspace just two devices:
> * power supply charger device (merged values from isp1707 and bq24150a)
> * power supply battery device (merged values from rx51_battery and bq27200)
> 
> Problem is that e.g. design capacity value provide both drivers. But
> bq27xxx just return constant and incorrect value from bq eeprom. Correct
> design capacity return only rx51_battery (which read it via ADC, third
> battery pin).
> 
> That should fix detection and discovery problem. On Nokia N900 there is
> just one battery and one charger device.
> 

Right, so there is no need to append each type of power-supply device
with a number, as there is only one of each type of power-supply, they
can still be uniquely identified. And if ever a product comes out that
has two or more of the same power-supply then they can be identified by
the I2C address they are attached to.

Number them in the name would not even work as it would change depending
on probe order and not based on which battery is which.

Andrew