From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grygorii Strashko Subject: Re: [PATCH] gpio: zynq: Implement irq_(request|release)_resources Date: Tue, 27 Oct 2015 19:54:40 +0200 Message-ID: <562FBA60.70002@ti.com> References: <1445607381-7794-1-git-send-email-soren.brinkmann@xilinx.com> <562FA3EE.5040408@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from comal.ext.ti.com ([198.47.26.152]:50216 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754492AbbJ0RzG (ORCPT ); Tue, 27 Oct 2015 13:55:06 -0400 In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Linus Walleij Cc: Soren Brinkmann , Alexandre Courbot , "linux-kernel@vger.kernel.org" , "linux-gpio@vger.kernel.org" , Michal Simek , "linux-arm-kernel@lists.infradead.org" , John Linn On 10/27/2015 06:23 PM, Linus Walleij wrote: > On Tue, Oct 27, 2015 at 5:18 PM, Grygorii Strashko > wrote: >> On 10/27/2015 05:53 PM, Linus Walleij wrote: >>> >>> On Fri, Oct 23, 2015 at 3:36 PM, Soren Brinkmann >>> 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 >>>> Signed-off-by: Soren Brinkmann >>>> Tested-by: John Linn >>> >>> >>> 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(). > > Do you mean that these functions contain calls to non-atomic > functions? > Oh. No, I have to be more specific :( if GPIOx driver defines custom .irq_(request|release)_resources() callbacks they will *overwrite* standard GPIOirqchip callbacks. (commit: 8b67a1f "gpio: don't override irq_*_resources() callbacks") As result, such GPIOx driver should *re-implement* the same functionality in its .irq_(request|release)_resources() callbacks as implemented in gpiochip_irq_reqres()/gpiochip_irq_relres(). > I mainly reacted to this because it was pm_* calls, that you > mentioned explicitly in your patch. > -- regards, -grygorii