linux-kernel - [PATCH 0/1] power: supply: bq27xxx: expose battery data when CI=1

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Message-Id: <20220419213647.1186284-1-absicsz@gmail.com>
Date:   Tue, 19 Apr 2022 23:36:46 +0200
From:   "Sicelo A. Mhlongo" <absicsz@...il.com>
To:     sre@...nel.org, pali@...nel.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Sicelo A. Mhlongo" <absicsz@...il.com>
Subject: [PATCH 0/1] power: supply: bq27xxx: expose battery data when CI=1

We currently discard capacity information provided by the chip when the
Capacity Inaccurate flag is set. However, in many cases, having this
stale data is better than no information at all.

Even if the chip has been fully reset, the datasheet shows that capacity 
values (NAC specifically) can be seeded by using the WRTNAC facility of 
the Control and Mode registers. After seeding, CI remains set, but the
capacity values are as accurate as the NAC value provided to WRTNAC is.

On the Nokia N900, such seed value can be obtained from rx51_battery, 
which reads battery data directly from the battery's BSI pin. This can
be done in userspace via i2c access to the registers. With this patch,
once seeded, capacity values are available through the driver.

The patch was successfully tested on bq27200 on the Nokia N900.

Signed-off-by: Sicelo A. Mhlongo <absicsz@...il.com>

Sicelo A. Mhlongo (1):
  power: supply: bq27xxx: expose battery data when CI=1

 drivers/power/supply/bq27xxx_battery.c | 58 +++++++++++++-------------
 1 file changed, 28 insertions(+), 30 deletions(-)

-- 
2.35.2