linux-kernel - Re: [PATCH v3 2/3] usb: phy: Add USB charger support

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Date:   Wed, 26 Jul 2017 11:19:00 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Manu Gautam <mgautam@...eaurora.org>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Sebastian Reichel <sre@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, Jun Li <jun.li@....com>,
        Peter Chen <peter.chen@...escale.com>,
        Mark Brown <broonie@...nel.org>,
        John Stultz <john.stultz@...aro.org>,
        NeilBrown <neilb@...e.com>, patches@...nsource.wolfsonmicro.com,
        Linux PM list <linux-pm@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>,
        device-mainlining@...ts.linuxfoundation.org,
        LKML <linux-kernel@...r.kernel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 2/3] usb: phy: Add USB charger support

Hi Manu,

On 25 July 2017 at 19:19, Manu Gautam <mgautam@...eaurora.org> wrote:
> Hi,
>
>
> On 7/25/2017 1:30 PM, Baolin Wang wrote:
>> This patch introduces the usb charger support based on usb phy that
>> makes an enhancement to a power driver. The basic conception of the
>> usb charger is that, when one usb charger is added or removed by
>> reporting from the extcon device state change, the usb charger will
>> report to power user to set the current limitation.
>>
>> Power user can register a notifiee on the usb phy by issuing
>> usb_register_notifier() to get notified by charger status changes
>> or charger current changes.
>
> Why can't we use power_supply framework for this?
> Power user can register usb power_supply and USB PHY driver
> can update charging current using - power_supply_set_property().

No. We can get the current can be drawn from USB layer not from power
supply framework, moreover some USB controller can detect the charger
type and power supply framework can not. I think you missed lots of
previous discussion, maybe you can check below links to follow what we
have discussed before.
https://lists.gt.net/linux/kernel/2546730
https://patchwork.kernel.org/patch/9601973/


>> we can notify what current to be drawn to power user according to
>> different charger type, and now we have 2 methods to get charger type.
>> One is get charger type from extcon subsystem, which also means the
>> charger state changes. Another is we can get the charger type from
>> USB controller detecting or PMIC detecting, and the charger state
>> changes should be told by issuing usb_phy_set_charger_state().
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> ---
>>  drivers/usb/phy/phy.c   |  272 +++++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/usb/phy.h |   49 +++++++++
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>



-- 
Baolin.wang
Best Regards