Re: [v5 PATCH 1/5] extcon: Add Type-C and DP support

Chanwoo Choi
2016-07-14T00:50:11Z

Hi Chris,

On 2016년 07월 13일 11:54, Chris Zhong wrote:
> Hi Chanwoo Choi
>
> On 07/13/2016 10:05 AM, Chanwoo Choi wrote:
>> Hi Chris,
>>
>> On 2016년 07월 13일 10:39, Chris Zhong wrote:
>>> Hi Chanwoo Choi
>>>
>>>
>>> On 07/13/2016 09:11 AM, Chanwoo Choi wrote:
>>>> Hi Chris,
>>>>
>>>> I'm now developing the extcon property on extcon-test branch.
>>>> But, it has not been completed.
>>>>
>>>> On next version, I'll remove the notification about extcon property
>>>> and only support the following two functions.
>>>> - extcon_set_cable_property()
>>>> - extcon_get_cable_property()
>>>>
>>>> Because the number of properties would be risen and the all properties
>>>> depend on the specific external connector(e.g., EXTCON_PROP_USB_VBUS
>>>> depend on the EXTCON_TYPE_USB type). When the specific external connector
>>>> is detached, extcon framework should make the property state as default state.
>>> Yes, I think getting the notification from cable state is enough, actually I am using it like you said.
>> OK.
>>
>>>> It may send the too many notification for extcon property.
>>>> For example, Assume that EXTCON_TYPE_USB has the over 20 properties,
>>>> when EXTCON_USB or EXTCON_USB_HOST is detached, extcon should send
>>>> the notification for the over 20 properties and one more notificaiton
>>>> for state of external connector.
>>>>
>>>> So, I'll send the RFC patchset without the notification of proerty.
>>>>
>>>> Lastly,
>>>> I have a comment on below.
>>>>
>>>> Thanks,
>>>> Chanwoo Choi
>>>>
>>>> On 2016년 07월 13일 00:09, Chris Zhong wrote:
>>>>> Add EXTCON_DISP_DP for the Display external connector. For Type-C
>>>>> connector the DisplayPort can work as an Alternate Mode(VESA DisplayPort
>>>>> Alt Mode on USB Type-C Standard). The Type-C support both normal and
>>>>> flipped orientation, so add a property to extcon.
>>>>>
>>>>> Signe-off-by: Chris Zhong <zyw@rock-chips.com>
>>>>>
>>>>> Signed-off-by: Chris Zhong <zyw@rock-chips.com>
>>>>> ---
>>>>>
>>>>> Changes in v5:
>>>>> - support get property
>>>>>
>>>>> Changes in v4: None
>>>>> Changes in v3: None
>>>>> Changes in v2: None
>>>>> Changes in v1: None
>>>>>
>>>>> drivers/extcon/extcon.c | 28 ++++++++++++++++++++++++++++
>>>>> include/linux/extcon.h | 13 +++++++++++++
>>>>> 2 files changed, 41 insertions(+)
>>>>>
>>>>> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
>>>>> index a1117db..2591b28 100644
>>>>> --- a/drivers/extcon/extcon.c
>>>>> +++ b/drivers/extcon/extcon.c
>>>>> @@ -157,6 +157,11 @@ struct __extcon_info {
>>>>> .id = EXTCON_DISP_VGA,
>>>>> .name = "VGA",
>>>>> },
>>>>> + [EXTCON_DISP_DP] = {
>>>>> + .type = EXTCON_TYPE_DISP,
>>>>> + .id = EXTCON_DISP_DP,
>>>>> + .name = "DP",
>>>>> + },
>>>>> /* Miscellaneous external connector */
>>>>> [EXTCON_DOCK] = {
>>>>> @@ -270,6 +275,7 @@ static bool is_extcon_property_supported(unsigned int id,
>>>>> switch (prop) {
>>>>> case EXTCON_PROP_USB_ID:
>>>>> case EXTCON_PROP_USB_VBUS:
>>>>> + case EXTCON_PROP_TYPEC_POLARITY:
>>>>> return true;
>>>>> default:
>>>>> break;
>>>>> @@ -286,6 +292,8 @@ static bool is_extcon_property_supported(unsigned int id,
>>>>> }
>>>>> case EXTCON_TYPE_DISP:
>>>>> switch (prop) {
>>>>> + case EXTCON_PROP_TYPEC_POLARITY:
>>>> Should EXTCON_PROP_TYPEC_POLARITY property add to both EXTCON_TYPE_USB and EXTCON_TYP_DISP?
>>>> EXTCON_PROP_TYPEC_POLARITY is the property of USB C-type?
>>> it is for USB Type-C, But at Display Port alt mode, both EXTCON_USB and EXTCON_USB_HOST may be detached. Does it support set the property to a detached cable, if so, I think move this case to EXTCON_USB is fine.
>> One external connector can set the state of one more external connector
>> if the one connector support the various functions.
>> For example, EXTCON_USB and EXTCON_CHG_USB_SDP
>> The existing extcon driver[1](e.g., max14577/max77693 etc.) set the state of both EXTCON_USB and EXTCON_CHG_USB_SDP connector at the same time
>> when usb cable is attached. Because in this case, the usb connector uses as both power supply(EXTCON_CHG_USB_SDP) and data transfer(EXTCON_USB).
>> [1] https://git.kernel.org/cgit/linux/kernel/git/chanwoo/extcon.git/commit/?h=extcon-next&id=8b45b6a0741678902810d7be95e635c210fbb198
>>
>> So, DP Alt mode uses the USB Type-C. So, When USB C-type connector is attached for DP Alt mode,
>> Maybe, you can set the following two state of connector and one property:
>> - extcon_set_cable_state(edev, [EXTCON_USB or EXTCON_USB_HOST], 1);
>> - extcon_set_cable_state(edev, EXTCON_DISP_DP, 1);
>> - extcon_set_cable_state(edev, [EXTCON_USB or EXTCON_USB_HOST], EXTCON_PROP_TYPEC_POLARITY, 0 or 1);
>>
>> Thanks,
>> Chanwoo Choi
>
> There are 4 modes for Type-C DP alt mode:
> 1) USB host only :
>
> extcon_set_cable_state(edev, EXTCON_USB_HOST, 1);
> extcon_set_cable_state(edev, EXTCON_USB, 0);
> extcon_set_cable_state(edev, EXTCON_DISP_DP, 0);
>
> 2) USB device only
>
> extcon_set_cable_state(edev, EXTCON_USB_HOST, 0);
> extcon_set_cable_state(edev, EXTCON_USB, 1);
> extcon_set_cable_state(edev, EXTCON_DISP_DP, 0);
>
> 3) DP only
>
> extcon_set_cable_state(edev, EXTCON_USB_HOST, 0);
> extcon_set_cable_state(edev, EXTCON_USB, 0);
> extcon_set_cable_state(edev, EXTCON_DISP_DP, 1);
>
> 4) USB + DP
>
> extcon_set_cable_state(edev, EXTCON_USB_HOST, 1);
> extcon_set_cable_state(edev, EXTCON_USB, 0);
> extcon_set_cable_state(edev, EXTCON_DISP_DP, 1);
>
>
> for 3rd mode: DP only, there is only EXTCON_DISP_DP is attached, the EXTCON_USB_HOST
> and EXTCON_USB are detached, Can I set the property into these 2 detached cable?
> or just call extcon_set_cable_state(edev, EXTCON_DISP_DP, EXTCON_PROP_TYPEC_POLARITY, 0 or 1);

I'm thinking to solve this issue. In result, we can add one more type to specific connector.
For EXTCON_DISP_DP, we can add the two type as following. And EXTCON_PROP_TYPEC_POLARITY property
should be added to EXTCON_TYPE_USB.

+ [EXTCON_DISP_DP] = {
+ .type = EXTCON_TYPE_DISP | EXTCON_TYPE_USB,
+ .id = EXTCON_DISP_DP,
+ .name = "DP",
+ },

So, as you mentioned, EXTCON_DISP_DP can set the EXTCON_PROP_TYPEC_POLARITY property as following:
- extcon_set_cable_state(edev, EXTCON_DISP_DP, EXTCON_PROP_TYPEC_POLARITY, 0 or 1);

I'll again developing the extcon property.

Thanks,
Chanwoo Choi