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Date: Tue, 23 Sep 2014 12:13:55 +0200
Message-ID: <CACRpkdZZ-8MAXQ_T2CYyUb0pcdS707G+NCWTc0oHJ2eqr-dcUA@mail.gmail.com>
Subject: Re: [PATCH 1/2] gpio / CrystalCove: support virtual GPIO
From: Linus Walleij <linus.walleij@linaro.org>
To: Aaron Lu <aaron.lu@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Darren Hart <dvhart@linux.intel.com>
Cc: Alexandre Courbot <gnurou@gmail.com>, Samuel Ortiz <sameo@linux.intel.com>,
        Lee Jones <lee.jones@linaro.org>, Arnd Bergmann <arnd@arndb.de>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Lejun Zhu <lejun.zhu@intel.com>,
        Radivoje Jovanovic <radivoje.jovanovic@intel.com>,
        =?UTF-8?Q?Daniel_Gl=C3=B6ckner?= <dg@emlix.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
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On Tue, Sep 9, 2014 at 4:32 AM, Aaron Lu <aaron.lu@intel.com> wrote:

> The virtual GPIO introduced in ACPI table of Baytrail-T based system is
> used to solve a problem under Windows. We do not have such problems
> under Linux so we do not actually need them. But we have to tell GPIO
> library that the Crystal Cove GPIO chip has this many GPIO pins or the
> common GPIO handler will refuse any access to those high number GPIO
> pins, which will resulted in a failure evaluation of every ACPI control
> method that is used to turn on/off power resource and/or report sensor
> temperatures.
>
> Due to the high number of virtual GPIOs, the value of ARCH_NR_GPIOS is
> bumped from 256 to 512 to avoid failures on platforms that have various
> GPIO controllers.
>
> Signed-off-by: Aaron Lu <aaron.lu@intel.com>

I have some other patch pending increasing the default GPIO# to
512, but anyhow: this needs review from someone. Where is
Lejun? Mika also reviewed last time. Someone I trust to understand
ACPI need to be involved, Rafael, Darren....

Yours,
Linus Walleij