From: Chanwoo Choi <cw00.choi@samsung.com>
To: "Ivan T. Ivanov" <iivanov@mm-sol.com>
Cc: Roger Quadros <rogerq@ti.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Robert Baldyga <r.baldyga@samsung.com>,
Peter Chen <peter.chen@freescale.com>,
Kishon Vijay Abraham I <kishon@ti.com>,
Felipe Balbi <balbi@ti.com>,
"myungjoo.ham@samsung.com" <myungjoo.ham@samsung.com>
Subject: Re: [PATCH v2 1/2] extcon: Add extcon_set_cable_line_state() to inform the additional state of external connectors
Date: Fri, 29 May 2015 16:58:34 +0900 [thread overview]
Message-ID: <55681C2A.6090105@samsung.com> (raw)
In-Reply-To: <1432805845.2348.33.camel@mm-sol.com>
On 05/28/2015 06:37 PM, Ivan T. Ivanov wrote:
> Hi,
>
> On Thu, 2015-05-28 at 18:17 +0900, Chanwoo Choi wrote:
>>
>>
>> 2015년 5월 28일 목요일, Ivan T. Ivanov<iivanov@mm-sol.com>님이 작성한 메시지:
>>> Hi Chanwoo,
>>>
>>> On Thu, 2015-05-28 at 00:06 +0900, Chanwoo Choi wrote:
>>>> On Wed, May 27, 2015 at 11:38 PM, Roger Quadros <rogerq@ti.com> wrote:
>>>>> Chanwoo,
>>>>>
>>>>> On 27/05/15 15:15, Chanwoo Choi wrote:
>>>>>> This patch adds the extcon_set_cable_line_state() function to inform
>>>>>> the additional state of each external connector and 'enum
>>>>>> extcon_line_state'
>>>>>> enumeration which include the specific states of each external connector.
>>>>>>
>>>>>> The each external connector might need the different line state. So,
>>>>>> current
>>>>>> 'extcon_line_state' enumeration contains the specific state for USB as
>>>>>> following:
>>>>>>
>>>>>> - Following the state mean the state of both ID and VBUS line for USB:
>>>>>> enum extcon_line_state {
>>>>>> EXTCON_USB_ID_LOW = BIT(1), /* ID line is low. */
>>>>>> EXTCON_USB_ID_HIGH = BIT(2), /* ID line is high. */
>>>>>
>>>>>
>>>>> ID_LOW and ID_HIGH cannot happen simultaneously so they can use the same bit
>>>>> position.
>>>>> if the bit is set means it is high, if it is cleared means it is low.
>>>>
>>>> These are the notifier event. So, extcon_line_state have to include
>>>> each event for both low or high state of ID.
>>>> because the extcon consumer driver using the
>>>> extcon_register_notifier() need the each event to distinguish the type
>>>> of event.
>>>>
>>>>>> EXTCON_USB_VBUS_LOW = BIT(3), /* VBUS line is low. */
>>>>>> EXTCON_USB_VBUS_HIGH = BIT(4), /* VBUS line is high. */
>>>>>
>>>>>
>>>>> same here.
>>>>
>>>> ditto.
>>>>
>>>>> enum doesn't look like the right type for extcon_line_state as it is more of
>>>>> a bitmask.
>>>>
>>>> Why? I prefer to use the enum if there are no problem.
>>>
>> If you insist your opinion, you shoud suggest the reason. Could you tell me the reason?
>
> It looks unreadable. There is no need to mix interface API (enum extcon_line_state)
> with implementation details. You can use plain enum at interface level and hide
> shifting inside implementation.
OK, I define it instead of enum.
>
>>
>>
>>>>>>
>>>>>> +enum extcon_line_state {
>>>>>> + /* Following two definition are used for whether external
>>>>>> connectors
>>>>>> + * is attached or detached. */
>>>>>> + EXTCON_DETACHED = 0x0,
>>>>>> + EXTCON_ATTACHED = 0x1,
>>>>>> +
>>>>>> + /* Following states are only used for EXTCON_USB. */
>>>>>> + EXTCON_USB_ID_LOW = BIT(1), /* ID line is low. */
>>>>>> + EXTCON_USB_ID_HIGH = BIT(2), /* ID line is high. */
>>>>>> + EXTCON_USB_VBUS_LOW = BIT(3), /* VBUS line is low. */
>>>>>> + EXTCON_USB_VBUS_HIGH = BIT(4), /* VBUS line is high. */
>>>>>> +};
>>>>>
>>>>>
>>>>> Why do you use enum? How about the following bit definitions for line state.
>>>>>
>>>>> #define EXTCON_ATTACHED_DETACHED_BIT BIT(0)
>>>>> #define EXTCON_USB_ID_BIT BIT(1)
>>>>> #define EXTCON_USB_VBUS_BIT BIT(2)
>>>>> ...
>>>>>
>>>>> code must check if appropriate bit is set or cleared to get the high/low
>>>>> state.
>>>>
>>>> I answer about it on upper.
>>>>
>>>
>>> Funny. We can use the one bit for DETACHED/ATTACHED, but we
>> hmm. Did you read my answer about low/high?
>>
>> But, I'm considering again about using the detached/attached value.
>
> Ok, but consumers will receive one event at time, right?
Yes.
Cheers,
Chanwoo Choi
next prev parent reply other threads:[~2015-05-29 7:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-27 12:15 [PATCH v2 0/2] extcon: Inform the state of both ID and VBUS pin for USB Chanwoo Choi
2015-05-27 12:15 ` [PATCH v2 1/2] extcon: Add extcon_set_cable_line_state() to inform the additional state of external connectors Chanwoo Choi
2015-05-27 14:38 ` Roger Quadros
2015-05-27 15:06 ` Chanwoo Choi
2015-05-28 9:02 ` Ivan T. Ivanov
[not found] ` <CAGTfZH2rn7OfqaTmr0d5-MfWW3ZFdt05_7vtLKqbEQee53999w@mail.gmail.com>
2015-05-28 9:37 ` Ivan T. Ivanov
2015-05-29 7:58 ` Chanwoo Choi [this message]
2015-05-27 12:15 ` [PATCH v2 2/2] extcon: usb-gpio: Update the ID pin state of USB when cable state is changed Chanwoo Choi
2015-05-27 14:40 ` Roger Quadros
2015-05-27 14:09 ` [PATCH v2 0/2] extcon: Inform the state of both ID and VBUS pin for USB Roger Quadros
2015-05-27 14:19 ` Chanwoo Choi
2015-05-28 8:45 ` Ivan T. Ivanov
2015-05-28 14:23 ` Roger Quadros
2015-05-29 1:22 ` Peter Chen
2015-05-29 10:53 ` Chanwoo Choi
2015-05-29 12:15 ` Chanwoo Choi
2015-06-02 6:51 ` Roger Quadros
2015-05-29 7:35 ` Ivan T. Ivanov
2015-05-29 7:36 ` Ivan T. Ivanov
2015-05-29 10:39 ` Chanwoo Choi
2015-05-29 10:44 ` Chanwoo Choi
2015-05-29 14:32 ` Ivan T. Ivanov
2015-05-29 17:15 ` Chanwoo Choi
2015-05-29 17:39 ` Chanwoo Choi
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