On Wed, Aug 30, 2017 at 11:58 PM, H. Nikolaus Schaller
[off-list ref] wrote:

Hi Liam,

quoted

Am 30.08.2017 um 13:24 schrieb Liam Breck [off-list ref]:

Hi Nikolaus,

On Wed, Aug 30, 2017 at 2:30 AM, H. Nikolaus Schaller [off-list ref] wrote:

quoted

Hi Liam and Sebastian,

quoted

Am 29.08.2017 um 22:20 schrieb Liam Breck [off-list ref]:

Hi Nikolaus, thanks for the patch...

On Tue, Aug 29, 2017 at 1:10 PM, H. Nikolaus Schaller [off-list ref] wrote:

quoted

Tested on Pyra prototype with bq27421.

Signed-off-by: H. Nikolaus Schaller <redacted>
---
drivers/power/supply/bq27xxx_battery.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
index b6c3120ca5ad..e3c878ef7c7e 100644
--- a/drivers/power/supply/bq27xxx_battery.c
+++ b/drivers/power/supply/bq27xxx_battery.c

@@ -688,7 +688,7 @@ static struct bq27xxx_dm_reg bq27545_dm_regs[] = {

#define bq27545_dm_regs 0
#endif

-#if 0 /* not yet tested */
+#if 1 /* tested on Pyra */
static struct bq27xxx_dm_reg bq27421_dm_regs[] = {

I think we can drop the #if and #else...#endif so it's just the
dm_regs table, as with bq27425.

I have fixed that and did take the chance to update my OpenPandora
kernel so that I also could test and make the bq27500 working.

Is this gauge on the board or in the battery?

It is on the board.

quoted

If in the battery,
monitored-battery should not be used.

For a gauge on the board, if a user changes the battery to a different
type, they need to update the dtb.

Well, that is a little difficult to control, but here we have only
one standard Pandora cell. There may exist replacements with different
capacity, but that should not be our problem...

quoted

I assume you built with config_battery_bq27xxx_dt_updates_nvm?

Yes.

quoted

quoted

The biggest hurdle was to find out that I have to change the
compatible string to "ti,bq27500-1" to get non-NULL dm_regs...

[   12.765930] bq27xxx_battery_i2c_probe name=bq27500-1-0
[   12.771392] bq27xxx_battery_i2c_probe call setup
[   12.874816] bq27xxx_battery_setup
[   12.904266] bq27xxx_battery_setup: dm_regs=bf0520e0
[   12.933380] (NULL device *): hwmon: 'bq27500-1-0' is not a valid name attribute, please fix
[   13.234893] bq27xxx_battery_settings
[   13.238891] bq27xxx-battery 2-0055: invalid battery:energy-full-design-microwatt-hours 14800000

The chip does not support this param, so it should be zero, as it has
to be set if charge-full-design-* is set. Can you try that?

Hm. IMHO the DT should describe what the battery has and the driver should simply ignore
values it can't handle or reject them but do the best out of it. Telling the driver to ignore
a value by setting to 0 would IMHO be the wrong approach.

The driver requires that if either charge- or energy-full-design is
set, then the other must be. Setting one and leaving the other at
default would be an error. Allowing any value for a field unsupported
by the chip, when supported field values must be within a range, isn't
useful for hw development or production scenarios. The solution for
shipped equipment is to drop the monitored-battery ref; see below.

We are also working on the generic-adc-battery driver that makes use of the same battery DT
node so that people can choose if they want to configure a kernel for fuel gauge or
g-a-b or even both.

quoted

quoted

[   13.312469] bq27xxx_battery_set_config
[   13.407745] bq27xxx_battery_unseal
[   13.455993] bq27xxx_battery_update_dm_block
[   13.460418] bq27xxx-battery 2-0055: update terminate-voltage to 3200
[   13.694885] bq27xxx_battery_seal

We need to see output after a reboot.

This was the value after first boot with the new driver enabled.

A second boot after removing and reinserting battery shows:

[   11.256713] bq27xxx_battery_setup
[   11.256744] bq27xxx_battery_setup: dm_regs=bf05b0e0
[   11.257690] (NULL device *): hwmon: 'bq27500-1-0' is not a valid name attribute, please fix
[   11.258056] bq27xxx_battery_settings
[   11.258300] bq27xxx-battery 2-0055: invalid battery:energy-full-design-microwatt-hours 14800000
[   11.258300] bq27xxx_battery_set_config
[   11.258331] bq27xxx_battery_unseal

No mention of terminate-voltage in that run? Or is this truncated?
Looks like you didn't set energy-* to zero, so I can't tell if charge-* works.

quoted

Note that this chip has NVM so
these settings persist without power.

Yes I know. Up to now the bq27500 has been programmed during production test
by some special flashing tool. Now as the kernel driver has this capability,
we should make (optionally) use of it.

The kernel driver has this feature primarily for gauges that lack NVM.
It sets those without config_battery_bq27xxx_dt_updates_nvm. The NVM
programming feature is for hw development and/or production. I don't
recommend it for shipped equipment.

quoted

quoted

Does this look ok for

       bat: battery {
               compatible = "simple-battery", "openpandora-battery";
               voltage-min-design-microvolt = <3200000>;
               energy-full-design-microwatt-hours = <14800000>;
               charge-full-design-microamp-hours = <4000000>;
       };

?

I mainly had some initial doubts that it did not tell something like
"update design-capacity" to 4000 or "design-capacity has 4000"

Ah, I see:

                /* assume design energy & capacity are in same block */

This means the bq27500 never programs capacity because we can't specify energy.
So I't suggest to revise this rule and coupling of energy and capacity setting.

No, it failed to set charge-* because energy-* is out of range. Fix
that and it should just emit a warning about energy-* "buffer does not
match dm spec"

quoted

quoted

I will send a patch for enabling both fuel gauges and the omap3-pandora-common.dtsi asap.

You probably don't want this in upstream dts, as it only programs the
gauge if the kernel has the above config option. If the box runs a
stock distro, it won't work. A custom-built kernel with the above dts
programs the gauge unless the user sets the module param
dt_monitored_battery_updates_nvm=0. The requisite dtb should be
packaged with the custom-built kernel, and deployed with awareness of
the actual battery present.

Imho, DT can and should describe all properties of the standard OpenPandora
battery (and not missing registers of the bq27500).

Using this information or not should be defined by different defconfigs.

Just omit monitored-battery from the bq27500 node on shipped devices.
We shall not program NVM on a stock kernel. And unfortunately you
can't send an NVM gauge temporary params.

NB: the DT battery node is new and all the implications have not been
discovered.

This BQ27 feature was begun in December of last year, and I'm a little
tired of thinking about it. Feel free to suggest improvements, but be
aware that we might have already considered and rejected them :-)