From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-owner@vger.kernel.org>
Received: from mga02.intel.com ([134.134.136.20]:50133 "EHLO mga02.intel.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1726565AbeK2T6B (ORCPT <rfc822;stable@vger.kernel.org>);
        Thu, 29 Nov 2018 14:58:01 -0500
Date: Thu, 29 Nov 2018 10:53:19 +0200
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] gpiolib-acpi: Only defer request_irq for GpioInt
 ACPI event handlers
Message-ID: <20181129085319.GJ2296@lahna.fi.intel.com>
References: <20181128165756.20908-1-hdegoede@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181128165756.20908-1-hdegoede@redhat.com>
Sender: stable-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

On Wed, Nov 28, 2018 at 05:57:55PM +0100, Hans de Goede wrote:
> Commit 78d3a92edbfb ("gpiolib-acpi: Register GpioInt ACPI event handlers
> from a late_initcall") deferred the entire acpi_gpiochip_request_interrupt
> call for each event resource.
> 
> This means it also delays the gpiochip_request_own_desc(..., "ACPI:Event")
> call. This is a problem if some AML code reads the GPIO pin before we
> run the deferred acpi_gpiochip_request_interrupt, because in that case
> acpi_gpio_adr_space_handler() will already have called
> gpiochip_request_own_desc(..., "ACPI:OpRegion") causing the call from
> acpi_gpiochip_request_interrupt to fail with -EBUSY and we will fail to
> register an event handler.
> 
> acpi_gpio_adr_space_handler is prepared for acpi_gpiochip_request_interrupt
> already having claimed the pin, but the other way around does not work.
> 
> One example of a problem this causes, is the event handler for the OTG
> ID pin on a Prowise PT301 tablet not registering, keeping the port stuck
> in whatever mode it was in during boot and e.g. only allowing charging
> after a reboot.
> 
> This commit fixes this by only deferring the request_irq call and the
> initial run of edge-triggered IRQs instead of deferring all of
> acpi_gpiochip_request_interrupt.
> 
> Cc: stable@vger.kernel.org
> Fixes: 78d3a92edbfb ("gpiolib-acpi: Register GpioInt ACPI event ...")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>