linux-kernel - Re: RE: [PATCH 2/4] power_supply: Introduce generic psy charging driver

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Date:	Fri, 18 Jul 2014 04:25:04 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	"Tc, Jenny" <jenny.tc@...el.com>,
	Sebastian Reichel <sre@...nel.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	Pavel Machek <pavel@....cz>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	David Woodhouse <dwmw2@...radead.org>,
	David Cohen <david.a.cohen@...ux.intel.com>,
	"Pallala, Ramakrishna" <ramakrishna.pallala@...el.com>,
	우상정 <sangjung.woo@...sung.com>,
	최찬우 <cw00.choi@...sung.com>,
	이종화 <jonghwa3.lee@...sung.com>
Subject: Re: RE: [PATCH 2/4] power_supply: Introduce generic psy charging driver

From: Tc, Jenny<jenny.tc@...el.com>
>  
> > From: Sebastian Reichel [mailto:sre@...nel.org]
> > Sent: Friday, July 18, 2014 7:49 AM
> > To: Tc, Jenny
> > Cc: linux-kernel@...r.kernel.org; Dmitry Eremin-Solenikov; Pavel Machek; Anton
> > Vorontsov; David Woodhouse; David Cohen; Pallala, Ramakrishna;
> > myungjoo.ham@...sung.com
> > Subject: Re: [PATCH 2/4] power_supply: Introduce generic psy charging driver
> > 
> > Hi Jenny,
> > 
> > On Tue, Jul 08, 2014 at 11:34:19AM +0530, Jenny TC wrote:
> > > The Power Supply charging driver connects multiple subsystems to do
> > > charging in a generic way. The subsystems involves power_supply,
> > > thermal and battery communication subsystems (1wire). With this the
> > > charging is handled in a generic way.
> > >
> > > The driver makes use of different new features - Battery
> > > Identification interfaces, pluggable charging algorithms, charger cable arbitrations
> > etc.
> > > The patch also introduces generic interface for charger cable notifications.
> > > Charger cable events and capabilities can be notified using the
> > > generic power_supply_notifier chain.
> > >
> > > Overall this driver removes the charging logic out of the charger chip
> > > driver and the charger chip driver can just listen to the request from
> > > the power supply charging driver to set the charger properties. This
> > > can be implemented by exposing get_property and set property callbacks.
> > 
> > this seems to be a superset of charger-manager, which is already in the kernel. I
> > would prefer not to have two different charger mangement frameworks in the kernel.
> > 
> > I suggest to add features supported by charger-manager to power supply charging
> > driver and convert users of charger-manager to the improved driver.
> > 
> > I CC'd MyungJoo Ham, who wrote the charger-manager, so that he can also give
> > feedback.
> 
> We are back to the initial discussions we had in the list. The initial proposal
> was for the charger manager. The charger manager is more aligned to
> regulator framework, use private notification
> mechanisms(cm_notify_event,fullbatt_vchk etc) and relies more on
> platform data (struct charger_desc). This doesn't seems to be good to support plug in
> charger drivers, charging algorithms, battery identification drivers at runtime.

Then, the additional requirement is
- Online or runtime modification or probe of the platform data (use .ko?) for "plugin chargers & battery identification)
- Externally implement charging algorithms. (allow charger-manager to have an external funtion pointer?)

> Power supply charger driver is introduced to meet all these requirements by
> extending the existing power_supply subsystem features like
> power_supply_changed event, power_supply_register, power supply thermal
> throttling mechanism so that plugging new driver would be
> easy. Also the user interfaces would remain the same as power_supply subsystem.

- Replace (rewrite) charger-manager's private event handlers with power supply changed work?

For identifying plugin (external) chargers and feeding such information to
charger-manager, extcon might be a good interconnection, which is initially
designed for devices supporting differernt external chargers. (USB charger,
1.5A OEM charger, 1.0A 3rd party "popular" charger, ...)

> 
> Able to locate link on the discussion. 
> http://www.gossamer-threads.com/lists/linux/kernel/1562180.


Cheers,
MyungJoo


ps. CC'd related collegues as well. (Sangjung, Chanwoo, Jonghwa)

--
MyungJoo Ham (함명주), PHD
Frontier CS Lab, Software Center
Samsung Electronics
Cell: +82-10-6714-2858