On Tue, May 31, 2016 at 2:35 AM, Chanwoo Choi <cw00.choi@xxxxxxxxxxx> wrote:
> Hi Rob,
>
> On 2016년 05월 31일 15:44, Chanwoo Choi wrote:
>> On 2016년 05월 28일 00:29, Rob Herring wrote:
>>> On Thu, May 26, 2016 at 05:17:45PM +0530, Venkat Reddy Talla wrote:
>>>> Add the support for Device tree bindings of extcon-gpio driver.
>>>> The extcon-gpio device tree node must include the both 'extcon-id' and
>>>> 'gpios' property.
>>>
>>> I think extcon bindings are a mess in general...
>>>
>>>> For example:
>>>> usb_cable: extcon-gpio-0 {
>>>> compatible = "extcon-gpio";
>>>> extcon-id = <EXTCON_USB>;
>>>> gpios = <&gpio6 1 GPIO_ACTIVE_HIGH>;
>>>> }
>>>> ta_cable: extcon-gpio-1 {
>>>> compatible = "extcon-gpio";
>>>> extcon-id = <EXTCON_CHG_USB_DCP>;
>>>> gpios = <&gpio3 2 GPIO_ACTIVE_LOW>;
>>>> debounce-ms = <50>; /* 50 millisecond */
>>>> wakeup-source;
>>>> }
>>>
>>> This is all 1 logical connector, the USB connector. Why are you
>>> describing cables? Those are not part of the h/w and are dynamic.
>>> Describe this as a connector which is one thing (i.e. node). Use a
>>> compatible string that reflects the type of connector
>>> (usb-microab-connector), not the driver you want to use. Then define
>>> GPIO lines needed to provide state information like VBus, ID, charger
>>> modes and control lines like soft connect (D+ pullup enable), VBus
>>> enable, etc.
>>
>> You're right. The extcon-gpio driver will not use the "extcon-gpio" raw compatible.
>> As you commented[1], the each connector will have the unique name to use the extcon-gpio.c driver.
>> [1] https://lkml.org/lkml/2015/10/21/906
>>
>>
>> For example,
>> The extcon-gpio.c driver may have the different name including the h/w information
>> according to the kind of external connector.
>>
>> static const struct of_device_id gpio_extcon_of_match[] = {
>> {
>> .compatible = "extcon-chg-sdp", /* SDP charger connector */
>> .data = EXTCON_CHG_SDP_DATA,
>> }, {
>> .compatible = "extcon-chg-dcp", /* DCP charger connector */
>> .data = EXTCON_CHG_DCP_DATA,
>> }, {
>> .compatible = "extcon-jack-microphone", /* Microphone jack connector */
>> .data = EXTCON_JACK_MICROPHONE_DATA,
>> }, {
>> .compatible = "extcon-disp-hdmi", /* HDMI connector*/
>> .data = EXTCON_DISP_HDMI_DATA,
>> },
>> ......
>> };
>
> I reply it again.
>
> The extcon-gpio.c is very similar with existing gpio_keys.c driver[1]
> [1] drivers/input/keyboard/gpio_keys.c
There is a big difference in that each gpio-key is independent. The
only state is pressed or not. A USB connector has multiple pieces of
state information. You may be treating them independently, but I don't
think they should be.
> The gpio_keys.c driver use the following style to support the device-tree.
> It use the "gpio-keys" compatible and this dt node include the specific
> 'key code' such as 'extcon-id = <EXTCON_CHG_USB_DCP>;'
This is state information about what is currently attached. The
analogy with gpio-keys would be multiple key codes on one gpio which
would be broken...
>
> gpio_keys {
> compatible = "gpio-keys";
>
> power_key {
> gpios = <&gpx2 7 GPIO_ACTIVE_LOW>;
> linux,code = <KEY_POWER>;
> label = "power key";
> debounce-interval = <10>;
> wakeup-source;
> };
> };
>
> If the extcon-gpio.c driver should have the separate compatible according to
> the kind of external connector, the list of compatible name of extcon-gpio.c driver
> will be increased when new external connector is attached.
So? Different h/w needs different compatible strings.
But again, you are mixing describing the connector (only what is
soldered on a board) and state information (what is attached). Do not
put state information into DT (describe the gpio signals or chip that
provides the state information).
> The extcon-gpio.c driver can separate the kind of external connector
> by using the 'extcon-id' property.
This use of DT is just broken. Come up with another way.
Rob
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