Messages in this thread | | | Date | Fri, 29 May 2015 16:58:34 +0900 | From | Chanwoo Choi <> | Subject | Re: [PATCH v2 1/2] extcon: Add extcon_set_cable_line_state() to inform the additional state of external connectors |
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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
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