linux-kernel - Re: [PATCH] extcon: Modify the id and name of external connector

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Date:	Mon, 5 Oct 2015 13:49:01 +0300
From:	Roger Quadros <rogerq@...com>
To:	Chanwoo Choi <cw00.choi@...sung.com>,
	Chanwoo Choi <cwchoi00@...il.com>,
	<linux-kernel@...r.kernel.org>
CC:	<k.kozlowski@...sung.com>, <ramakrishna.pallala@...el.com>,
	<gregkh@...uxfoundation.org>,
	<ckeepax@...nsource.wolfsonmicro.com>,
	<rf@...nsource.wolfsonmicro.com>,
	<patches@...nsource.wolfsonmicro.com>, <myungjoo.ham@...sung.com>
Subject: Re: [PATCH] extcon: Modify the id and name of external connector

Chanwoo,

On 05/10/15 12:04, Chanwoo Choi wrote:
> Hi Roger,
> 
> On 2015년 10월 05일 18:01, Chanwoo Choi wrote:
>> Hi Roger,
>>
>> On 2015년 10월 05일 17:26, Roger Quadros wrote:
>>> Chanwoo,
>>>
>>> On 04/10/15 06:45, Chanwoo Choi wrote:
>>>> This patch modifies the id and name of external connector with the additional
>>>> prefix to clarify both attribute and meaning of external connector as following:
>>>> - EXTCON_CHG_* mean the charger connector.
>>>> - EXTCON_JACK_* mean the jack connector.
>>>> - EXTCON_DISP_* mean the display port connector.
>>>>
>>>> Following table show the new name of external connector with old name:
>>>> -------------------------------------------------
>>>> Old extcon name         | New extcon name       |
>>>> -------------------------------------------------
>>>> EXTCON_TA               | EXTCON_CHG_USB_DCP    |
>>>> EXTCON_FAST_CHARGER     | EXTCON_CHG_USB_FAST   |
>>>> EXTCON_SLOW_CHARGER     | EXTCON_CHG_USB_SLOW   |
>>>> EXTCON_CHARGE_DOWNSTREAM| EXTCON_CHG_USB_CDP    |
>>>> -------------------------------------------------
>>>> EXTCON_MICROPHONE       | EXTCON_JACK_MICROPHONE|
>>>> EXTCON_HEADPHONE        | EXTCON_JACK_HEADPHONE |
>>>> EXTCON_LINE_IN          | EXTCON_JACK_LINE_IN   |
>>>> EXTCON_LINE_OUT         | EXTCON_JACK_LINE_OUT  |
>>>> EXTCON_VIDEO_IN         | EXTCON_JACK_VIDEO_IN  |
>>>> EXTCON_VIDEO_OUT        | EXTCON_JACK_VIDEO_OUT |
>>>> EXTCON_SPDIF_IN         | EXTCON_JACK_SPDIF_IN  |
>>>> EXTCON_SPDIF_OUT        | EXTCON_JACK_SPDIF_OUT |
>>>> -------------------------------------------------
>>>> EXTCON_HMDI             | EXTCON_DISP_HDMI      |
>>>> EXTCON_MHL              | EXTCON_DISP_MHL       |
>>>> EXTCON_DVI              | EXTCON_DISP_DVI       |
>>>> EXTCON_VGA              | EXTCON_DISP_VGA       |
>>>> -------------------------------------------------
>>>>
>>>> And, when altering the name of USB charger connector, EXTCON refers to the
>>>> "USB battery charging specification"[1] to use the standard name of USB
>>>> charging port as following. Following name of USB charging port are already used
>>>> in power_supply subsystem. We chan check it on patch[2].
>>>> - EXTCON_CHG_USB	/* Standard Downstream Port */
>>>> - EXTCON_CHG_USB_DCP	/* Dedicated Charging Port */
>>>> - EXTCON_CHG_USB_CDP	/* Charging Downstream Port */
>>>> - EXTCON_CHG_USB_ACA	/* Accessory Charging Adapter */
>>>>
>>>> [1] http://www.usb.org/developers/docs/devclass_docs/USB_Battery_Charging_1.2.pdf
>>>> [2] commit 85efc8a18ce ("[PATCH] power_supply: Add types for USB chargers")
>>>>
>>>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>>>> ---
>>>>  drivers/extcon/extcon-arizona.c  | 18 ++++++------
>>>>  drivers/extcon/extcon-axp288.c   | 12 ++++----
>>>>  drivers/extcon/extcon-max14577.c | 18 ++++++------
>>>>  drivers/extcon/extcon-max77693.c | 32 +++++++++++----------
>>>>  drivers/extcon/extcon-max77843.c | 27 ++++++++++--------
>>>>  drivers/extcon/extcon-max8997.c  | 21 +++++++-------
>>>>  drivers/extcon/extcon-rt8973a.c  |  4 +--
>>>>  drivers/extcon/extcon-sm5502.c   |  4 +--
>>>>  drivers/extcon/extcon.c          | 60 ++++++++++++++++++++-------------------
>>>>  include/linux/extcon.h           | 61 +++++++++++++++++++++++-----------------
>>>>  10 files changed, 138 insertions(+), 119 deletions(-)
>>>>
>>>
>>> <snip>
>>>
>>>> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
>>>> index 8dd0af1..505a028 100644
>>>> --- a/drivers/extcon/extcon.c
>>>> +++ b/drivers/extcon/extcon.c
>>>> @@ -39,37 +39,39 @@
>>>>  #define CABLE_NAME_MAX		30
>>>>  
>>>>  static const char *extcon_name[] =  {
>>>> -	[EXTCON_NONE]		= "NONE",
>>>> +	[EXTCON_NONE]		= "EXTCON_NONE",
>>>>  
>>>>  	/* USB external connector */
>>>> -	[EXTCON_USB]		= "USB",
>>>> -	[EXTCON_USB_HOST]	= "USB-HOST",
>>>> -
>>>> -	/* Charger external connector */
>>>> -	[EXTCON_TA]		= "TA",
>>>> -	[EXTCON_FAST_CHARGER]	= "FAST-CHARGER",
>>>> -	[EXTCON_SLOW_CHARGER]	= "SLOW-CHARGER",
>>>> -	[EXTCON_CHARGE_DOWNSTREAM] = "CHARGE-DOWNSTREAM",
>>>> -
>>>> -	/* Audio/Video external connector */
>>>> -	[EXTCON_LINE_IN]	= "LINE-IN",
>>>> -	[EXTCON_LINE_OUT]	= "LINE-OUT",
>>>> -	[EXTCON_MICROPHONE]	= "MICROPHONE",
>>>> -	[EXTCON_HEADPHONE]	= "HEADPHONE",
>>>> -
>>>> -	[EXTCON_HDMI]		= "HDMI",
>>>> -	[EXTCON_MHL]		= "MHL",
>>>> -	[EXTCON_DVI]		= "DVI",
>>>> -	[EXTCON_VGA]		= "VGA",
>>>> -	[EXTCON_SPDIF_IN]	= "SPDIF-IN",
>>>> -	[EXTCON_SPDIF_OUT]	= "SPDIF-OUT",
>>>> -	[EXTCON_VIDEO_IN]	= "VIDEO-IN",
>>>> -	[EXTCON_VIDEO_OUT]	= "VIDEO-OUT",
>>>> -
>>>> -	/* Etc external connector */
>>>> -	[EXTCON_DOCK]		= "DOCK",
>>>> -	[EXTCON_JIG]		= "JIG",
>>>> -	[EXTCON_MECHANICAL]	= "MECHANICAL",
>>>> +	[EXTCON_USB]		= "EXTCON_USB",
>>>> +	[EXTCON_USB_HOST]	= "EXTCON_USB_HOST",
>>>> +
>>>> +	/* Charging external connector */
>>>> +	[EXTCON_CHG_USB]	= "EXTCON_CHG_USB",
>>>> +	[EXTCON_CHG_USB_FAST]	= "EXTCON_CHG_USB_FAST",
>>>> +	[EXTCON_CHG_USB_SLOW]	= "EXTCON_CHG_USB_SLOW",
>>>
>>> How does FAST & SLOW correlate to USB specifications?
>>
>> There is no specification about FAST & SLOW USB charger.
>> Just, the datasheet of MUIC (Micro-USB Interface Circuit) device
>> can detect the DCP (Dedicated Charging Port) and more two type charger
>> according to current value as following:
>>
>> For example,
>> max77693 MUIC device (is used on Samsung Galaxy S3)
>> - CHG_USB_DCP: current up to 1.5A
>> - CHG_USB_SLOW : current up to 500mA
>> - CHG_USB_FAST : current up to 1A or 2A
>>
>> max77836 MUIC device (is used on Samsung gear 2)
>> - CHG_USB_DCP: current up to 1.5A
>> - CHG_USB_SLOW : current up to 500mA
>> - CHG_USB_FAST : current up to 1A or 2A
>>
>> max77843 MUIC device (is used on Samsung Galaxy Note4)
>> - CHG_USB_DCP: current up to 1.5A
>> - CHG_USB_SLOW : current up to 500mA
>> - CHG_USB_FAST : current up to 1A or 2A
>>
>> If MUIC device detects the some USB charger which
>> has the more maximum current than DCP, this muic device
>> call the FAST charger. Also, there is oppsite case for SLOW charger.
> 
> I think that following name is more appropriate than old name.
> - EXTCON_CHG_USB_SLOW -> EXTCON_CHG_USB_DCP_SLOW
> - EXTCON_CHG_USB_FAST -> EXTCON_CHG_USB_DCP_FAST
> 

Yes that looks more appropriate.

> 
>>
>>>
>>>> +	[EXTCON_CHG_USB_DCP]	= "EXTCON_CHG_USB_DCP",
>>>> +	[EXTCON_CHG_USB_CDP]	= "EXTCON_CHG_USB_CDP",
>>>
>>> What about USB ACA?
>>
>> ACA is "Accessory Charging Adapter". But, I didn't understand the role
>> of ACA charger type. I'll drop ACA type on next version.

ACA is typically used by a docking station which can charge the
embedded host (e.g. mobile phone) as well as allow connecting a
USB peripheral to it.

The link you gave above for Battery charging spec is in fact just the compliance plan.
The spec is actually available here
http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip

cheers,
-roger
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