linux-kernel - Re: [PATCH 1/4] extcon: Add USB VBUS properties

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Message-ID: <bfa20bf2-e13b-1cd4-52d9-c8fa922d5aac@samsung.com>
Date:   Tue, 15 Sep 2020 10:40:28 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Angus Ainslie <angus@...ea.ca>, kernel@...i.sm
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        bryan.odonoghue@...aro.org
Subject: Re: [PATCH 1/4] extcon: Add USB VBUS properties

Hi,

On 9/15/20 1:46 AM, Angus Ainslie wrote:
> USB type C, USB BC1.2 and USB power delivery allow different voltages
> and currents for VBUS so we need these additional properties.
> 
> Also USB type C allows separate device and power roles so add a VBUS SRC
> property.
> 
> Signed-off-by: Angus Ainslie <angus@...ea.ca>
> ---
>  include/linux/extcon.h | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/extcon.h b/include/linux/extcon.h
> index fd183fb9c20f..c4d48f4f74c4 100644
> --- a/include/linux/extcon.h
> +++ b/include/linux/extcon.h
> @@ -117,14 +117,29 @@
>   * @type:       integer (intval)
>   * @value:      0 (USB/USB2) or 1 (USB3)
>   * @default:    0 (USB/USB2)
> + * - EXTCON_PROP_USB_VBUS_SRC

Could you explain more correct meaning of both sink and source?

> + * @type:	integer (intval)
> + * @value:	0 (sink) or 1 (source)
> + * @default:	0 (sink)
> + * - EXTCON_PROP_USB_VBUS_VOLTAGE
> + * @type:	integer (intval)
> + * @value:	negotiated vbus voltage in mV
> + * @default:	5000

Could you suggest the data why do you set default value as 5000?

> + * - EXTCON_PROP_USB_VBUS_CURRENT
> + * @type:	integer (intval)
> + * @value:	negotiated vbus current in mA
> + * @default:	100

ditto. Why default value is 100?

>   *
>   */
>  #define EXTCON_PROP_USB_VBUS		0
>  #define EXTCON_PROP_USB_TYPEC_POLARITY	1
>  #define EXTCON_PROP_USB_SS		2
> +#define EXTCON_PROP_USB_VBUS_SRC	3
> +#define EXTCON_PROP_USB_VBUS_VOLTAGE	4
> +#define EXTCON_PROP_USB_VBUS_CURRENT	5
>  
>  #define EXTCON_PROP_USB_MIN		0
> -#define EXTCON_PROP_USB_MAX		2
> +#define EXTCON_PROP_USB_MAX		5
>  #define EXTCON_PROP_USB_CNT	(EXTCON_PROP_USB_MAX - EXTCON_PROP_USB_MIN + 1)
>  
>  /* Properties of EXTCON_TYPE_CHG. */
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics