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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Darren Hart <dvhart@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [RFC PATCH] gpio: support for GPIO forwarding
Date: Thu, 22 Jan 2015 17:12:07 +0100	[thread overview]
Message-ID: <4006695.qV8Mor20ru@vostro.rjw.lan> (raw)
In-Reply-To: <CACRpkdZpUU71suzt9JhiBZez2VuJ6-Zm3D1uvmn71bjdn=oU_A@mail.gmail.com>

On Thursday, January 22, 2015 09:17:38 AM Linus Walleij wrote:
> On Tue, Jan 20, 2015 at 10:25 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> 
> > Yes, it can (in principle).  In fact, we have a plan to refine it, but it is
> > going to take some time.  Once we've done that, we'll see how painful it is to
> > "patch" ACPI tables this way in practice.
> >
> > Also there is an ecosystem problem related to distributing such "patches".
> > Today, distributions don't need to worry about patching buggy platform
> > firmware, because they get workarounds in the kernel, but if we switch over
> > to the model in which platform firmware "overlays" need to be provided in
> > addition to it, then suddenly questions arise about who should be responsible
> > for making them available, how to avoid duplication of efforts between
> > distributions etc.
> >
> > All of that needs to be clarified before we start making hard statements like
> > "No in-kernel workarounds for that!"
> 
> OK so why can't the patching happen in the kernel?
> 
> If the kernel anyway has to supply some kind of workaround for
> the issue, it is more a question of where to place it. Whether it does
> so by patching the ACPI tables or by detecting a bad ACPI thing
> and working around it at runtime in a certain driver doesn't really
> matter, does it?

It needs to know what to patch and how so the result is still consistent.

How do you think the kernel is going to figure that out?

> They are both in-kernel ACPI fixes, just that one
> of the mechanisms is generic.

I'm not following you here, sorry.

> I don't understand why this obsession with userspace having
> to do the ACPI table patching - if kernels should "just work" then
> put this stuff behind Kconfig and have it in the kernel.

This is not an obsession and your suggestion here leads to having custom
per-board kernels which is not supportable in the long term.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

  reply	other threads:[~2015-01-22 15:49 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 [this message]
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
2015-02-12 12:38                       ` Heikki Krogerus

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