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From: Alexandre Courbot <email@example.com>
To: Heikki Krogerus <firstname.lastname@example.org>
Cc: Linus Walleij <email@example.com>,
"Rafael J. Wysocki" <firstname.lastname@example.org>,
"Rafael J. Wysocki" <email@example.com>,
Darren Hart <firstname.lastname@example.org>,
Arnd Bergmann <email@example.com>,
Andy Shevchenko <firstname.lastname@example.org>,
Mika Westerberg <email@example.com>,
ACPI Devel Maling List <firstname.lastname@example.org>
Subject: Re: [RFC PATCH] gpio: support for GPIO forwarding
Date: Tue, 10 Feb 2015 18:44:34 +0900 [thread overview]
Message-ID: <CAAVeFu+JHMf__s0hfCJq31kZP-mp02bbzVywq+eZ9JVyP9boSw@mail.gmail.com> (raw)
On Wed, Feb 4, 2015 at 11:11 PM, Heikki Krogerus
> On Wed, Feb 04, 2015 at 10:51:27AM +0100, Linus Walleij wrote:
>> On Fri, Jan 30, 2015 at 5:17 PM, Rafael J. Wysocki <email@example.com> wrote:
>> > On Friday, January 30, 2015 03:48:30 PM Linus Walleij wrote:
>> >> So you could detect one by making a checksum of the binary or something.
>> >> And then you'd know that the table with this checksum needs patching?
>> > At a single table level it is generally difficult to say whether or not
>> > things are going to work.
>> > What needs to work is the namespace which is built from all of the tables
>> > provided combined. So the namespace needs to be populated first and then
>> > fixes applied on top of that (presumably by deleting, adding or replacing
>> > objects).
>> > Now, in theory, you *may* be able to figure out that combination of tables
>> > A produces namespace B which then will require fix X if the system is Y,
>> > but quite frankly I wouldn't count on that.
>> > Moreover, fixups (or "patches" as I called them, but that wasn't exactly
>> > correct) need to be provided in the form of AML definition blocks to apply on
>> > top of an already populated namespace and if you want to use a binary kernel image,
>> > you can't really afford putting all that stuff for all systems it can possibly
>> > run on into it. This means that distros need to be able to combine a fixup for
>> > the ACPI tables with the binary kernel and install the result into the system's
>> > boot medium (whatever it is). Also it should be possible to update the fixup
>> > and the kernel image separately if necessary.
>> > Now from the kernel's perspective that raises the question: "What if the
>> > ACPI tables fixup provided by the distro is not sufficient?"
>> > That needs to be addressed somehow in the code.
>> Yeah I guess I'm convinced that we need to handle this particular
>> weirdness in the gpio-acpi code... if it can be contained there as
>> expressed by Alexandre.
> I'm still fine if we want to confine this "gpio forwarding" to acpi
> if you guys want it, but I was looking at the Sound SoC drivers and I
> realised that we do have places which pass gpio descriptors to other
> devices in platform data. And these of course aren't always used on
> acpi platforms. By greping gpio_desc I saw at least these files are
> passing it in platform data structures:
> There are probable others but I checked those. And of course now there
> is nothing preventing people from adding more of them.
For sound/soc.h, the member is indeed public but I don't see it being
used to pass descriptors around between drivers.
For linux/leds.h, I think this is the reason why we introduced
These looks more like a bad usage of GPIO descriptors, but AFAICT they
can be fixed by fixing the drivers and, by all means, this is where we
should do it.
This is a different situation from yours where we are trying to deal
with broken firmware and need to resort to tricks at one point or the
Or am I missing your point?
next prev parent reply other threads:[~2015-02-10 9:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-18 8:23 Heikki Krogerus
2015-01-08 8:25 ` Heikki Krogerus
2015-01-15 9:21 ` Rafael J. Wysocki
2015-01-14 12:58 ` Linus Walleij
2015-01-14 16:32 ` Darren Hart
2015-01-15 9:28 ` Rafael J. Wysocki
2015-01-15 9:40 ` Heikki Krogerus
2015-01-14 16:32 ` Darren Hart
2015-01-19 5:59 ` Alexandre Courbot
2015-01-19 11:53 ` Heikki Krogerus
2015-01-20 12:16 ` Linus Walleij
2015-01-20 21:25 ` Rafael J. Wysocki
2015-01-22 2:57 ` Alexandre Courbot
2015-01-22 16:14 ` Rafael J. Wysocki
2015-01-23 11:21 ` Heikki Krogerus
2015-01-23 15:14 ` Rafael J. Wysocki
2015-01-26 13:06 ` Heikki Krogerus
2015-02-10 9:32 ` Alexandre Courbot
2015-02-10 15:10 ` Rafael J. Wysocki
2015-02-12 12:46 ` Heikki Krogerus
2015-02-24 20:34 ` David Cohen
2015-02-25 1:34 ` Alexandre Courbot
2015-02-25 18:25 ` David Cohen
2015-03-07 22:13 ` Linus Walleij
2015-01-22 8:17 ` Linus Walleij
2015-01-22 16:12 ` Rafael J. Wysocki
2015-01-30 14:48 ` Linus Walleij
2015-01-30 16:17 ` Rafael J. Wysocki
2015-02-04 9:51 ` Linus Walleij
2015-02-04 14:11 ` Heikki Krogerus
2015-02-10 9:44 ` Alexandre Courbot [this message]
2015-02-12 12:38 ` Heikki Krogerus
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