On Mon, Feb 14, 2022 at 11:12 AM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > > On Fri, Feb 11, 2022 at 3:30 AM Won Chung <wonchung@xxxxxxxxxx> wrote: > > > > When ACPI table includes _PLD fields for a device, create a new > > directory (pld) in sysfs to share _PLD fields. > > This version of the patch loos better to me, but I'm not sure if it > goes into the right direction overall. > > > Currently without PLD information, when there are multiple of same > > devices, it is hard to distinguish which device corresponds to which > > physical device in 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. > > So I think that this is your primary use case and I'm wondering if > this is the best way to address it. > > Namely, by exposing _PLD information under the ACPI device object, > you'll make user space wanting to use that information depend on this > interface, but the problem is not ACPI-specific (inevitably, it will > appear on systems using DT, sooner or later) and making the user space > interface related to it depend on ACPI doesn't look like a perfect > choice. > > IOW, why don't you create a proper ABI for this in the Type C > subsystem and expose the information needed by user space in a generic > way that can be based on the _PLD information on systems with ACPI? Hi Rafael, Thank you for the review. I was thinking that _PLD info is specific to ACPI since it is part of the ACPI table. Could you explain a little bit more on why you think exposing _PLD fields is not an ACPI-specific problem? I gave an example of how _PLD fields can be used for specifying Type C connectors, but it is not Type C specific. For Chrome OS, we plan to initially add PLD to not only Type C connectors but also USB port devices (including Type C and Type A). Also, PLD can be used in the future for describing other types of ports too like HDMI. (Benson and Prashant, please correct or add if I am wrong or missing some information) Maybe my commit message was not detailed enough.. I am also curious what Heikki thinks about this. Heikki, can you take a look and share your thoughts? Thank you, Won
