linux-kernel - Re: [PATCH v2 13/20] power: supply: bq25890: Support higher charging voltages through Pump Express+ protocol

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Date:   Tue, 16 Nov 2021 12:40:26 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Mark Gross <markgross@...nel.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Sebastian Reichel <sre@...nel.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Ard Biesheuvel <ardb@...nel.org>, Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Yauhen Kharuzhy <jekhor@...il.com>,
        Tsuchiya Yuto <kitakar@...il.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: [PATCH v2 13/20] power: supply: bq25890: Support higher charging
 voltages through Pump Express+ protocol

Hi,

On 11/16/21 12:14, Andy Shevchenko wrote:
> On Sun, Nov 14, 2021 at 7:04 PM Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> From: Yauhen Kharuzhy <jekhor@...il.com>
>>
>> Add a "linux,pump-express-vbus-max" property which indicates if the Pump
>> Express+ protocol should be used to increase the charging protocol.
>>
>> If this new property is set and a DCP charger is detected then request
>> a higher charging voltage through the Pump Express+ protocol.
>>
>> So far this new property is only used on X86/ACPI (non devicetree) devs,
>> IOW it is not used in actual devicetree files. The devicetree-bindings
>> maintainers have requested properties like these to not be added to the
>> devicetree-bindings, so the new property is deliberately not added
>> to the existing devicetree-bindings.
>>
>> Changes by Hans de Goede:
>> - Port to my bq25890 patch-series + various cleanups
>> - Make behavior configurable through a new "linux,pump-express-vbus-max"
>>   device-property
>> - Sleep 1 second before re-checking the Vbus voltage after requesting
>>   it to be raised, to ensure that the ADC has time to sampled the new Vbus
>> - Add VBUSV bq25890_tables[] entry and use it in bq25890_get_vbus_voltage()
>> - Tweak commit message
> 
> ...
> 
>> +#define PUMP_EXPRESS_START_DELAY       (5 * HZ)
>> +#define PUMP_EXPRESS_MAX_TRIES         6
>> +#define PUMP_EXPRESS_VBUS_MARGIN       1000000
> 
> Units? Perhaps "_uV"?
> 
> ...
> 
>> +               dev_dbg(bq->dev, "input voltage = %d mV\n", voltage);
> 
> Just to be sure, is it indeed "mV" and not "uV"?

It is uV, will fix for the next version.

> 
> ...
> 
>> +               while (bq25890_field_read(bq, F_PUMPX_UP) == 1)
>> +                       msleep(100);
> 
> Infinite loop?
> 
> Sounds like a good candidate to switch to read_poll_timeout() // note> it accepts any type of (op) with a variadic number of args.

Good catch, will fix.

> 
> ...
> 
>> +error:
> 
> error_print: ?
> 
>> +       dev_err(bq->dev, "Failed to request hi-voltage charging\n");
> 
> ...
> 
>> +       ret = device_property_read_u32(bq->dev, "linux,pump-express-vbus-max",
>> +                                      &bq->pump_express_vbus_max);
>> +       if (ret < 0)
>> +               bq->pump_express_vbus_max = 0;
> 
> Isn't it 0 by default?
> 
> Anyway, for all optional properties one may use
> 
> bq->...property... = $default;
> device_property_read_u32(bq->dev, "linux,...property...", &bq->...property...);
> 
> I.e. no conditional needed.

Ack, will fix.

Regards,

Hans