From: Tony Lindgren <tony@atomide.com>
To: "Arthur D." <spinal.by@gmail.com>
Cc: Merlijn Wajer <merlijn@wizzup.org>, Pavel Machek <pavel@ucw.cz>,
sre@kernel.org, linux-pm@vger.kernel.org,
linux-omap@vger.kernel.org
Subject: Re: [PATCH 06/15] power: supply: cpcap-battery: Initialize with user provided data
Date: Sat, 21 Mar 2020 15:21:08 -0700 [thread overview]
Message-ID: <20200321222108.GX37466@atomide.com> (raw)
In-Reply-To: <op.0huns9h5hxa7s4@supervisor.net28>
* Arthur D. <spinal.by@gmail.com> [200321 22:09]:
> Hi.
>
> > Hmm I'm getting -EINVAL when I do echo 1600000 > charge_now but yet the
> > value does get updated?
>
> Hm. I'm getting "Permission denied" when trying to do this.
> Anyway, charge_now value is not supposed to be initialized by the user.
> Only charge_full should be writable.
Sorry I meant writing to charge_full :) Anyways, looks like echo -n works
with no errors:
# echo 1305000 > charge_full
bash: echo: write error: Invalid argument
# echo -n 1305000 > charge_full
> > And I'm still not seeing capacity show up after that though even with
> > full battery.. I think we should be able to calculate it if either a
> > high or
> > low value has been seen?
>
> There are two steps needed to calibrate the battery: to hit the "fully
> charged"
> state and to hit "battery empty" state. When the both states were hit the
> driver
> will initialize charge_full value. And it will start reporting correct
> charge_now
> and capacity (battery charge percentage) values.
Hmm OK. So far no luck triggering that though.
> Once the charge_full value is calculated it's recommended to be saved by the
> user
> to a permanent storage between reboots.
>
> Saving/restoring the value can be done in init scripts.
>
> For saving the calibration value just use the command like:
> cat /sys/class/power_supply/battery/charge_full > /battery_cf
>
> To restore (after device reboot or power on):
> cat /battery_cf > /sys/class/power_supply/battery/charge_full
OK
> This will allow the kernel to do fast calibration. I.e. you will
> only need to fully charge _OR_ fully discharge the battery to start
> seeing correct charge_now and capacity values.
OK
> > Also, we should have the driver default to using the charge_full_design
> > value if nothing is written from userspace and we see a high or low
> > value.
>
> I'd prefer to have charge_full value undefined until the battery is
> calibrated.
> This way the userspace can estimate current battery capacity using voltage
> as a
> fallback for uncalibrated battery. The voltage estimation will be way more
> accurate than having charge_full = charge_full_design on pretty old Droid 4
> batteries. For example, my battery after calibration has about 1000 mAh,
> while charge_full_design is 1740000.
OK
> > Maybe some pessimistic estimate could be used instead of just using
> > charge_full_design if no value is initialized from the userspace?
> > Something like (charge_full_design / 4) * 3 maybe?
>
> It's better to rely on voltage estimated percentage.
> In Maemo Leste we patched upower to use the following formula, which gives
> pretty
> good results:
>
> percentage = (voltage - voltage_empty) / (voltage_full - voltage_empty) *
> 100
>
> Actually, the formula we use is a bit more complicated.
OK
> If you're curious, here's how it's actually done:
> https://github.com/maemo-leste/upower/blob/master/src/linux/up-device-supply.c#L756
Thanks, I'll give the calibration another try. Maybe I did not wait low
enough, I think I went down to 3.3V.
Regards,
Tony
next prev parent reply other threads:[~2020-03-21 22:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-15 15:11 [PATCH 01/15] power: supply: cpcap-battery: Fix battery full status reporting Arthur Demchenkov
2020-03-15 15:11 ` [PATCH 02/15] power: supply: cpcap-battery: Improve battery full status detection Arthur Demchenkov
2020-03-15 16:46 ` Tony Lindgren
2020-03-15 15:11 ` [PATCH 03/15] power: supply: cpcap-battery: Fix battery low status reporting Arthur Demchenkov
2020-03-21 14:47 ` Tony Lindgren
2020-03-21 21:40 ` Arthur D.
2020-03-15 15:11 ` [PATCH 04/15] power: supply: cpcap-battery: Add charge_full property Arthur Demchenkov
2020-03-15 15:11 ` [PATCH 05/15] power: supply: cpcap-battery: Add charge_now property Arthur Demchenkov
2020-03-15 15:11 ` [PATCH 06/15] power: supply: cpcap-battery: Initialize with user provided data Arthur Demchenkov
2020-03-21 14:54 ` Tony Lindgren
2020-03-21 22:08 ` Arthur D.
2020-03-21 22:21 ` Tony Lindgren [this message]
2020-03-15 15:11 ` [PATCH 07/15] power: supply: cpcap-battery: Rewrite capacity reporting Arthur Demchenkov
2020-03-15 15:11 ` [PATCH 08/15] power: supply: cpcap-battery: Get rid of rough capacity percentage Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 09/15] power: supply: cpcap-battery: Increse low voltage bound Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 10/15] power: supply: cpcap-battery: Improve full status reporting Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 11/15] power: supply: cpcap-battery: Rename properties, variables and functions Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 12/15] power: supply: cpcap-battery: stabilize charge_full value Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 13/15] power: supply: cpcap-battery: Fine tune end of charge current Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 14/15] power: supply: cpcap-battery: Make it behave like bq27200 Arthur Demchenkov
2020-03-15 15:12 ` [PATCH 15/15] power: supply: cpcap-battery: Add rounding to capacity reporting Arthur Demchenkov
2020-03-15 18:58 ` [PATCH 01/15] power: supply: cpcap-battery: Fix battery full status reporting Pavel Machek
2020-03-15 19:19 ` Tony Lindgren
2020-03-15 20:51 ` Arthur D.
2020-03-15 21:59 ` Tony Lindgren
2020-03-16 1:30 ` Arthur D.
2020-03-16 16:02 ` Tony Lindgren
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