linux-kernel - Re: [PATCH v2] usb:typec: Add sysfs support for Type C connector's physical location

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Date:   Tue, 1 Mar 2022 11:33:50 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Won Chung <wonchung@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Benson Leung <bleung@...omium.org>,
        Prashant Malani <pmalani@...omium.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb:typec: Add sysfs support for Type C connector's
 physical location

Hi Won,

On Tue, Mar 01, 2022 at 02:26:25AM +0000, Won Chung wrote:
> When ACPI table includes _PLD field for a Type C connector, share _PLD
> values in its sysfs. _PLD stands for physical location of device.
> 
> Currently without connector's location information, when there are
> multiple Type C ports, it is hard to distinguish which connector
> corresponds to which physical port at which location. For example, when
> there are two Type C connectors, it is hard to find out which connector
> corresponds to the Type C port on the left panel versus the Type C port
> on the right panel. With location information provided, we can determine
> which specific device at which location is doing what.
> 
> _PLD output includes much more fields, but only generic fields are added
> and exposed to sysfs, so that non-ACPI devices can also support it in
> the future. The minimal generic fields needed for locating a port are
> the following.
> - panel
> - vertical_position
> - horizontal_position
> - dock
> - lid
> 
> Signed-off-by: Won Chung <wonchung@...gle.com>
> ---
> 
> Changes in v2:
> - Use string for location.
> - Clarify get_pld() with naming and return type.
> 
>  Documentation/ABI/testing/sysfs-class-typec |  35 ++++++
>  drivers/usb/typec/class.c                   | 113 ++++++++++++++++++++
>  drivers/usb/typec/class.h                   |   3 +
>  3 files changed, 151 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec
> index 75088ecad202..4497a5aeb063 100644
> --- a/Documentation/ABI/testing/sysfs-class-typec
> +++ b/Documentation/ABI/testing/sysfs-class-typec
> @@ -141,6 +141,41 @@ Description:
>  		- "reverse": CC2 orientation
>  		- "unknown": Orientation cannot be determined.
>  
> +What:		/sys/class/typec/<port>/location/panel
> +Date:		March 2022
> +Contact:	Won Chung <wonchung@...gle.com>
> +Description:
> +		Describes which panel surface of the system’s housing the
> +		port resides on.
> +
> +What:		/sys/class/typec/<port>/location/vertical_position
> +Date:		March 2022
> +Contact:	Won Chung <wonchung@...gle.com>
> +Description:
> +		Describes vertical position of the port on the panel surface.
> +		Valid values: upper, center, lower
> +
> +What:		/sys/class/typec/<port>/location/horizontal_position
> +Date:		March 2022
> +Contact:	Won Chung <wonchung@...gle.com>
> +Description:
> +		Describes horizontal position of the port on the panel surface.
> +		Valid values: left, center, right
> +
> +What:		/sys/class/typec/<port>/location/dock
> +Date:		March 2022
> +Contact:	Won Chung <wonchung@...gle.com>
> +Description:
> +		Set as "yes" if the port resides in a docking station or a port
> +		replicator, otherwise set as "no".
> +
> +What:		/sys/class/typec/<port>/location/lid
> +Date:		March 2022
> +Contact:	Won Chung <wonchung@...gle.com>
> +Description:
> +		Set as "yes" if the port resides on the lid of laptop system,
> +		otherwise set as "no".
> +

I've probable lost track of the topic during my winter break, I'm
sorry about that, but why are you proposing now that this should be
made Type-C specific?
This information is not Type-C specific, so it definitely does not
belong here.

Br,

-- 
heikki