From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S965151AbbJ0QTY (ORCPT <rfc822;w@1wt.eu>);
	Tue, 27 Oct 2015 12:19:24 -0400
Received: from bear.ext.ti.com ([192.94.94.41]:53203 "EHLO bear.ext.ti.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S965011AbbJ0QTW (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 27 Oct 2015 12:19:22 -0400
Subject: Re: [PATCH] gpio: zynq: Implement irq_(request|release)_resources
To: Linus Walleij <linus.walleij@linaro.org>,
        Soren Brinkmann <soren.brinkmann@xilinx.com>
References: <1445607381-7794-1-git-send-email-soren.brinkmann@xilinx.com>
 <CACRpkda4QKEJvwkwGLS7OLTP8Nxu5W05tzbcFXA_FPnBsFtKhw@mail.gmail.com>
CC: Alexandre Courbot <gnurou@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
        Michal Simek <michal.simek@xilinx.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        John Linn <linnj@xilinx.com>
From: Grygorii Strashko <grygorii.strashko@ti.com>
Message-ID: <562FA3EE.5040408@ti.com>
Date: Tue, 27 Oct 2015 18:18:54 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <CACRpkda4QKEJvwkwGLS7OLTP8Nxu5W05tzbcFXA_FPnBsFtKhw@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/27/2015 05:53 PM, Linus Walleij wrote:
> On Fri, Oct 23, 2015 at 3:36 PM, Soren Brinkmann
> <soren.brinkmann@xilinx.com> wrote:
>
>> The driver uses runtime PM to leverage low power techniques. For
>> use-cases using GPIO as interrupt the device needs to be in an
>> appropriate state.
>>
>> Reported-by: John Linn <linnj@xilinx.com>
>> Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
>> Tested-by: John Linn <linnj@xilinx.com>
>
> As pointed out by Grygorii in
> commit aca82d1cbb49af34b69ecd4571a0fe48ad9247c1:
>
>      The PM runtime API can't be used in atomic contex on -RT even if
>      it's configured as irqsafe. As result, below error report can
>      be seen when PM runtime API called from IRQ chip's callbacks
>      irq_startup/irq_shutdown/irq_set_type, because they are
>      protected by RAW spinlock:
> (...)
>      The IRQ chip interface defines only two callbacks which are executed in
>      non-atomic contex - irq_bus_lock/irq_bus_sync_unlock, so lets move
>      PM runtime calls there.
>
> I.e. these calls are atomic context and it's just luck that it works
> and this is fragile.
>
> Can you please check if you can move it to
> irq_bus_lock()/irq_sync_unlock()
> like Grygorii does?
>

This patch rises the question not only about PM runtime, but also
about gpiochip_irq_reqres()/gpiochip_irq_relres().


-- 
regards,
-grygorii