Letux Kernel

Issue 717: bq27xxx driver

Reported by Nikolaus Schaller, Apr 9, 2016

The Pyra has a bq27621 fuel gauge chip. This assumes a nominal 
capacity by design of 2450 mAh.

The Pyra battery has 6000 mAh which should be defined in the device 
tree node of the bq27621 chip (or a battery subnode).

To fix the calculations of empty/full battery the driver

http://lxr.free-electrons.com/source/drivers/power/bq27xxx_battery.c

should reprogram the bq27621 chip during probing (or if it finds a 
mismatch of registers 0x3C and 0x3D).

The procedure to update the DESIGN_CAPACITY register is described 
here:

http://www.ti.com/lit/ug/sluuad4c/sluuad4c.pdf

see section "3.1 Data Memory Parameter Update Example" on 
page 12.

A good solution appears to be to patch

http://lxr.free-electrons.com/source/drivers/power/bq27xxx_battery.c#
L714

by adding a check if the design capacity matches a DT node entry and 
try a reprogram on mismatch.

Comment 1 by Nikolaus Schaller, Apr 9, 2016

Status: Duplicate

Created: 4 years 1 month ago by Nikolaus Schaller

Updated: 4 years 1 month ago

Status: Duplicate

Labels:
Type:Defect
Priority:Critical