From: Won Chung <wonchung@google.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Benson Leung <bleung@chromium.org>,
Prashant Malani <pmalani@chromium.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6] ACPI: device_sysfs: Add sysfs support for _PLD
Date: Mon, 14 Feb 2022 12:30:17 -0800 [thread overview]
Message-ID: <CAOvb9yjpruiHxkZyZ8BOT0Hi_iV7xMOnBCr59BZX3eah_Zcy_w@mail.gmail.com> (raw)
In-Reply-To: <CAJZ5v0gD4zs3uBAYv6M4_1gNpkZ-g9XKOywJnf5007e6GwoGVA@mail.gmail.com>
On Mon, Feb 14, 2022 at 11:12 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Fri, Feb 11, 2022 at 3:30 AM Won Chung <wonchung@google.com> 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
next prev parent reply other threads:[~2022-02-14 21:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-11 2:30 [PATCH v6] ACPI: device_sysfs: Add sysfs support for _PLD Won Chung
2022-02-14 19:11 ` Rafael J. Wysocki
2022-02-14 20:30 ` Won Chung [this message]
2022-02-14 22:58 ` Won Chung
2022-02-15 10:14 ` Heikki Krogerus
2022-02-15 13:54 ` Rafael J. Wysocki
2022-02-16 11:34 ` Heikki Krogerus
2022-02-16 16:39 ` Rafael J. Wysocki
2022-02-18 1:15 ` Won Chung
2022-02-18 17:24 ` Rafael J. Wysocki
2022-02-18 19:48 ` Won Chung
2022-02-28 19:12 ` Won Chung
2022-02-15 14:04 ` Rafael J. Wysocki
2022-02-15 14:08 ` Rafael J. Wysocki
2022-02-16 17:33 ` Greg Kroah-Hartman
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