[PATCH 1/2] dt-bindings: power: supply: ab8500_fg: Add line impedance

[PATCH 1/2] dt-bindings: power: supply: ab8500_fg: Add line impedance

[Linus Walleij]

To improve the inner resistance measurement of the battery we need
to account for the line impedance of the connector to the battery.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 .../bindings/power/supply/stericsson,ab8500-fg.yaml          | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/supply/stericsson,ab8500-fg.yaml b/Documentation/devicetree/bindings/power/supply/stericsson,ab8500-fg.yaml
index 54ac42a9d354..2ce408a7c0ae 100644
--- a/Documentation/devicetree/bindings/power/supply/stericsson,ab8500-fg.yaml
+++ b/Documentation/devicetree/bindings/power/supply/stericsson,ab8500-fg.yaml
@@ -25,6 +25,11 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     deprecated: true
 
+  line-impedance-micro-ohms:
+    description: The line impedance between the battery and the
+      AB8500 inputs, to compensate for this when determining internal
+      resistance.
+
   interrupts:
     maxItems: 5
 
-- 
2.34.1

[PATCH 2/2] power: supply: ab8500_fg: Account for line impedance

[Linus Walleij]

We add the line impedance to the inner resistance determined
from the battery voltage or other means to improve the
capacity estimations.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/power/supply/ab8500_fg.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/power/supply/ab8500_fg.c b/drivers/power/supply/ab8500_fg.c
index 1abe10c7ff2a..3ae8086907de 100644
--- a/drivers/power/supply/ab8500_fg.c
+++ b/drivers/power/supply/ab8500_fg.c
@@ -213,6 +213,7 @@ struct ab8500_fg {
 	int init_cnt;
 	int low_bat_cnt;
 	int nbr_cceoc_irq_cnt;
+	u32 line_impedance_uohm;
 	bool recovery_needed;
 	bool high_curr_mode;
 	bool init_capacity;
@@ -910,6 +911,9 @@ static int ab8500_fg_battery_resistance(struct ab8500_fg *di, int vbat_uncomp_uv
 		resistance = bi->factory_internal_resistance_uohm / 1000;
 	}
 
+	/* Compensate for line impedance */
+	resistance += (di->line_impedance_uohm / 1000);
+
 	dev_dbg(di->dev, "%s Temp: %d battery internal resistance: %d"
 	    " fg resistance %d, total: %d (mOhm)\n",
 		__func__, di->bat_temp, resistance, di->bm->fg_res / 10,
@@ -3098,6 +3102,11 @@ static int ab8500_fg_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (!of_property_read_u32(dev->of_node, "line-impedance-micro-ohms",
+				  &di->line_impedance_uohm))
+		dev_info(dev, "line impedance: %u uOhm\n",
+			 di->line_impedance_uohm);
+
 	psy_cfg.supplied_to = supply_interface;
 	psy_cfg.num_supplicants = ARRAY_SIZE(supply_interface);
 	psy_cfg.drv_data = di;
-- 
2.34.1

Re: [PATCH 1/2] dt-bindings: power: supply: ab8500_fg: Add line impedance

[Rob Herring]

On Tue, Mar 01, 2022 at 01:42:53PM +0100, Linus Walleij wrote:
> To improve the inner resistance measurement of the battery we need
> to account for the line impedance of the connector to the battery.
> 
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  .../bindings/power/supply/stericsson,ab8500-fg.yaml          | 5 +++++
>  1 file changed, 5 insertions(+)

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH 1/2] dt-bindings: power: supply: ab8500_fg: Add line impedance

[Sebastian Reichel]

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Hi,

On Wed, Mar 02, 2022 at 12:25:26PM -0600, Rob Herring wrote:
> On Tue, Mar 01, 2022 at 01:42:53PM +0100, Linus Walleij wrote:
> > To improve the inner resistance measurement of the battery we need
> > to account for the line impedance of the connector to the battery.
> > 
> > Cc: devicetree@vger.kernel.org
> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> > ---
> >  .../bindings/power/supply/stericsson,ab8500-fg.yaml          | 5 +++++
> >  1 file changed, 5 insertions(+)
> 
> Acked-by: Rob Herring <robh@kernel.org>

Thanks, queued (together with patch 2/2)

-- Sebastian

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