Re: Re: [PATCH] extcon : callback function to read cable property

From: MyungJoo Ham <myungjoo.ham@samsung.com>
To: Anton Vorontsov <cbouatmailru@gmail.com>,
	"Tc, Jenny" <jenny.tc@intel.com>
Cc: 최찬우 <cw00.choi@samsung.com>,
	"anish singh" <anish198519851985@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"myunjoo.ham@gmail.com" <myunjoo.ham@gmail.com>,
	"lockwood@android.com" <lockwood@android.com>,
	"peterhuewe@gmx.de" <peterhuewe@gmx.de>,
	"broonie@opensource.wolfsonmicro.com"
	<broonie@opensource.wolfsonmicro.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"lars@metafoo.de" <lars@metafoo.de>,
	"jic23@kernel.org" <jic23@kernel.org>,
	"Pallala, Ramakrishna" <ramakrishna.pallala@intel.com>
Subject: Re: Re: [PATCH] extcon : callback function to read cable property
Date: Tue, 20 Nov 2012 11:05:44 +0000 (GMT)	[thread overview]
Message-ID: <32212704.282601353409543335.JavaMail.weblogic@epml17> (raw)

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Anton Vorontsov wrote:
> The idea of using union seemed good to me, what happened to it?
> 
> I mean, MyungJoo Ham wrote:
> 
> | We may have:
> |        enum extcon_cable_type {
> |                EXTCON_CT_REGULATOR,
> |                EXTCON_CT_PSY,
> |                EXTCON_CT_CHARGER_CB,
> |                ...
> |        };
> | and have the following included at struct extcon_cable:
> |        union {
> |                struct regulator *reg;
> |                struct power_supply *psy;
> |                struct charger_cable *charger_cb;
> |                ...
> |        } cable data;
> |        enum extcon_cable_type cable_type;
> 
> This sounds good to me...
> 
> >  * extcon is not designed to support any cable state other than CONNECT/DISCONNECT
> 
> Dunno for this one. Can we get these additional states via "properties" as
> described above?
> 
> Thanks,
> Anton.
> 
> 

The "RFC" patch for this feature is now shown at:
http://git.kernel.org/?p=linux/kernel/git/mzx/extcon.git;a=commit;h=5655aeef83addaec77a3b9387a3dd18b6c146dd5
(Note that "for-add-feature" branch is sort of "RFC" branch)

I'm now considering relaying notifications of data updates possible via
the notifier block of register-interest. Any inputs are welcomed.

Anyway, for the USB issue of "suspend/resume at host-side and current-limit at
device-side", we will need to
1. update regulator subsystem to have notification for current change
(it does for enable/disable/voltage-changes)
2. let the charger use current-regulator
3. let the one who detects (usb driver?) changes at host-side change the
current limit of that current-regulator
4. let the event from current-regulator relayed via extcon.
We may use power-supply class as well for this issue. (may need to update
if power-supply class does not have notifications and suspend/resume states)

Cheers,
MyungJoo

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