Thread (62 messages) 62 messages, 12 authors, 2018-10-16

Re: [PATCH v7 3/4] dt-bindings: power: supply: qcom_bms: Add bindings

From: Craig <hidden>
Date: 2018-09-20 19:14:01
Also in: linux-arm-msm, linux-pm, lkml


On 20 September 2018 17:58:47 BST, Sebastian Reichel [off-list ref] wrote:
[Dropped a couple of people from CC, added Baolin]

Hi Craig, Baolin and Rob,

On Thu, Sep 20, 2018 at 03:32:29PM +0100, Craig wrote:
quoted
On 16 September 2018 13:10:45 BST, Sebastian Reichel
[off-list ref] wrote:
quoted
quoted
Sorry for my long delay in reviewing this. I like the binding,
but the "qcom," specific properties should become common properties
in

Documentation/devicetree/bindings/power/supply/battery.txt
and referenced via monitored-battery.
quoted
Thanks for the review, what bindings for ocv would you prefer? The
spreadtrum ones or mine?
Most importantly I want to see only one generic binding supporting
both use cases. As far as I can see there are two major differences:

1. Qcom uses legend properties and SC27XX embedds this into data
2. Qcom supports temperature based mapping

The second point is easy: Not having temperature information can
be a subset of the data with temperature info. The main thing to
discuss are the legend properties. I suppose we have these
proposals:

Proposal A (from Qcom BMS binding):

ocv-capacity-legend = /bits/ 8 <100 95 90 85 80 75 70 65 60 55 50 45
...>;
ocv-temp-legend-celsius = /bits/ 8 <(-10) 0 25 50 65>;
ocv-lut-microvolt = <43050000 43050000 43030000 42990000

Proposal B (from SC27XX binding):

ocv-cap-table = <4185 100>, <4113 95>, <4066 90>, <4022 85> ...;

I prefer the second binding (with mV -> uV), but I think it becomes
messy when temperature is added. What do you think about the
following proposal (derived from pinctrl style):

Proposal C:

ocv-capacity-table-temperatures = <(-10) 0 10>;
ocv-capacity-table-0 = <4185000 100>, <4113000 95>, <4066000 90>, ...;
ocv-capacity-table-1 = <4200000 100>, <4185000 95>, <4113000 90>, ...;
ocv-capacity-table-2 = <4250000 100>, <4200000 95>, <4185000 90>, ...;

-- Sebastian
C looks good to me however I do kinda think it should be millivolts as I don't think any hardware reads in microvolts and the zeroes make it look quite ugly
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