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Message-ID: <23f924be-a0ee-8efa-d92c-da83700261da@wizzup.org>
Date: Sat, 27 Jun 2020 13:01:53 +0200
From: Merlijn Wajer <merlijn@...zup.org>
To: Pavel Machek <pavel@....cz>,
kernel list <linux-kernel@...r.kernel.org>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
linux-omap@...r.kernel.org, tony@...mide.com, sre@...nel.org,
nekit1000@...il.com, mpartap@....net, martin_rysavy@...trum.cz,
linux-pm@...r.kernel.org
Subject: Re: [RFC] Limiting charge current on Droid 4 (and N900)
Hi Pavel,
On 15/06/2020 16:05, Pavel Machek wrote:
> Hi!
>
> Droid 4 has same problem as N900: it is often neccessary to manually
> tweak current draw from USB, for example when using thin charging cable.
>
> N900 creates unique attribute by hand, but I believe
> POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT looks suitable. (Should N900 be
> converted?)
>
> Comments? Would the patch be acceptable after fixing whitespace?
I'm not very knowledgeable on batteries - but the patch looks good to me.
Could you perhaps explain what exactly this fixes? I've seen some
interesting behaviour when plugging a Droid 4 into a PC (or wall
charger, really): the led blinks for a few seconds until it stabilises.
And then there's the issue where, once the battery is full, it will
switch between charging and discharging every few seconds/minutes.
Cheers,
Merlijn
>
> Best regards,
> Pavel
>
> Signed-off-by: Pavel Machek <pavel@....cz>
>
> diff --git a/drivers/power/supply/cpcap-battery.c b/drivers/power/supply/cpcap-battery.c
> index b16848cfb58c..39a00716372f 100644
> --- a/drivers/power/supply/cpcap-battery.c
> +++ b/drivers/power/supply/cpcap-battery.c
> @@ -3,7 +3,7 @@
> *
> * Copyright (C) 2017 Tony Lindgren <tony@...mide.com>
> *
> - * Some parts of the code based on earlie Motorola mapphone Linux kernel
> + * Some parts of the code based on earlier Motorola mapphone Linux kernel
> * drivers:
> *
> * Copyright (C) 2009-2010 Motorola, Inc.
> diff --git a/drivers/power/supply/cpcap-charger.c b/drivers/power/supply/cpcap-charger.c
> index cf1e05b511d9..292d7a31c663 100644
> --- a/drivers/power/supply/cpcap-charger.c
> +++ b/drivers/power/supply/cpcap-charger.c
> @@ -89,6 +89,8 @@
> * CPCAP_REG_CRM charge currents. These seem to match MC13783UG.pdf
> * values in "Table 8-3. Charge Path Regulator Current Limit
> * Characteristics" for the nominal values.
> + *
> + * Except 70mA and 1.596A and unlimited, these are simply 88.7mA / step.
> */
> #define CPCAP_REG_CRM_ICHRG(val) (((val) & 0xf) << 0)
> #define CPCAP_REG_CRM_ICHRG_0A000 CPCAP_REG_CRM_ICHRG(0x0)
> @@ -147,6 +149,8 @@ struct cpcap_charger_ddata {
> int status;
> int state;
> int voltage;
> + int limit_current;
> +
> int last_current;
> int last_current_retries;
> };
> @@ -175,6 +179,7 @@ static enum power_supply_property cpcap_charger_props[] = {
> POWER_SUPPLY_PROP_STATUS,
> POWER_SUPPLY_PROP_ONLINE,
> POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE,
> + POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> POWER_SUPPLY_PROP_VOLTAGE_NOW,
> POWER_SUPPLY_PROP_CURRENT_NOW,
> };
> @@ -238,6 +243,9 @@ static int cpcap_charger_get_property(struct power_supply *psy,
> case POWER_SUPPLY_PROP_STATUS:
> val->intval = ddata->status;
> break;
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + val->intval = ddata->limit_current;
> + break;
> case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> val->intval = ddata->voltage;
> break;
> @@ -308,6 +316,25 @@ cpcap_charger_get_bat_const_charge_voltage(struct cpcap_charger_ddata *ddata)
> return voltage;
> }
>
> +static int cpcap_charger_current_to_regval(int microamp)
> +{
> + int miliamp = microamp/1000;
> + int res;
> + if (miliamp < 0)
> + return -EINVAL;
> + if (miliamp < 70)
> + return CPCAP_REG_CRM_ICHRG(0x0);
> + if (miliamp < 177)
> + return CPCAP_REG_CRM_ICHRG(0x1);
> + if (miliamp > 1596)
> + return CPCAP_REG_CRM_ICHRG(0xe);
> +
> + res = microamp / 88666;
> + if (res > 0xd)
> + res = 0xd;
> + return CPCAP_REG_CRM_ICHRG(res);
> +}
> +
> static int cpcap_charger_set_property(struct power_supply *psy,
> enum power_supply_property psp,
> const union power_supply_propval *val)
> @@ -316,6 +343,12 @@ static int cpcap_charger_set_property(struct power_supply *psy,
> int voltage, batvolt;
>
> switch (psp) {
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> + if (cpcap_charger_current_to_regval(val->intval) < 0)
> + return -EINVAL;
> + ddata->limit_current = val->intval;
> + schedule_delayed_work(&ddata->detect_work, 0);
> + break;
> case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> voltage = cpcap_charger_match_voltage(val->intval);
> batvolt = cpcap_charger_get_bat_const_charge_voltage(ddata);
> @@ -335,6 +368,7 @@ static int cpcap_charger_property_is_writeable(struct power_supply *psy,
> enum power_supply_property psp)
> {
> switch (psp) {
> + case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> return 1;
> default:
> @@ -657,23 +691,21 @@ static void cpcap_usb_detect(struct work_struct *work)
>
> if (!ddata->feeding_vbus && cpcap_charger_vbus_valid(ddata) &&
> s.chrgcurr1) {
> - int max_current;
> - int vchrg;
> + int max_current = 532000;
> + int vchrg, ichrg;
>
> if (cpcap_charger_battery_found(ddata))
> - max_current = CPCAP_REG_CRM_ICHRG_1A596;
> - else
> - max_current = CPCAP_REG_CRM_ICHRG_0A532;
> + max_current = 1596000;
>
> switch (ddata->state) {
> case CPCAP_CHARGER_DETECTING:
> ddata->last_current_retries = 0;
> break;
> case CPCAP_CHARGER_DISCONNECTED:
> - if (ddata->last_current > CPCAP_REG_CRM_ICHRG_0A532) {
> + if (ddata->last_current > 532000) {
> /* Attempt current 3 times before lowering */
> if (ddata->last_current_retries++ >= 3) {
> - ddata->last_current--;
> + ddata->last_current -= 100000;
> ddata->last_current_retries = 0;
> /* Wait a bit for voltage to ramp up */
> usleep_range(40000, 50000);
> @@ -688,11 +720,16 @@ static void cpcap_usb_detect(struct work_struct *work)
> break;
> }
>
> + if (max_current > ddata->limit_current)
> + max_current = ddata->limit_current;
> +
> ddata->last_current = max_current;
> +
> + ichrg = cpcap_charger_current_to_regval(max_current);
> vchrg = cpcap_charger_voltage_to_regval(ddata->voltage);
> error = cpcap_charger_set_state(ddata,
> CPCAP_REG_CRM_VCHRG(vchrg),
> - max_current, 0);
> + ichrg, 0);
> if (error)
> goto out_err;
> cpcap_charger_update_state(ddata, CPCAP_CHARGER_CHARGING);
> @@ -864,6 +901,7 @@ static int cpcap_charger_probe(struct platform_device *pdev)
>
> ddata->dev = &pdev->dev;
> ddata->voltage = 4200000;
> + ddata->limit_current = 532000;
>
> ddata->reg = dev_get_regmap(ddata->dev->parent, NULL);
> if (!ddata->reg)
>
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