Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933443AbbGUV2t (ORCPT ); Tue, 21 Jul 2015 17:28:49 -0400 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:12085 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755409AbbGUV2s (ORCPT ); Tue, 21 Jul 2015 17:28:48 -0400 X-IronPort-AV: E=Sophos;i="5.15,519,1432623600"; d="scan'208";a="70518848" Message-ID: <55AEB91C.1020202@broadcom.com> Date: Tue, 21 Jul 2015 14:26:52 -0700 From: Florian Fainelli User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Thomas Gleixner , Florian Fainelli CC: Brian Norris , Gregory Fong , , , , Kevin Cernekee , Jason Cooper Subject: Re: [PATCH 1/2] genirq: add chip_{suspend,resume} PM support to irq_chip References: <20150619224123.GL4917@ld-irv-0074> <1434756403-379-1-git-send-email-computersforpeace@gmail.com> <55AE8E5D.8020700@gmail.com> In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4050 Lines: 88 On 21/07/15 14:23, Thomas Gleixner wrote: > On Tue, 21 Jul 2015, Florian Fainelli wrote: >> On 20/06/15 07:11, Thomas Gleixner wrote: >>> On Fri, 19 Jun 2015, Brian Norris wrote: >>>> This patch adds a second set of suspend/resume hooks to irq_chip, this >>>> time to represent *chip* suspend/resume, rather than IRQ suspend/resume. >>>> These callbacks will always be called for an irqchip and are based on >>>> the per-chip irq_chip_generic struct, rather than the per-IRQ irq_data >>>> struct. >>> >>> There is no per-chip irq_chip_generic struct. It's only there if the >>> irq chip has been instantiated as a generic chip. >>> >>>> /** >>>> * struct irq_chip - hardware interrupt chip descriptor >>>> * >>>> @@ -317,6 +319,12 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) >>>> * @irq_suspend: function called from core code on suspend once per chip >>>> * @irq_resume: function called from core code on resume once per chip >>>> * @irq_pm_shutdown: function called from core code on shutdown once per chip >>>> + * @chip_suspend: function called from core code on suspend once per >>>> + * chip; for handling chip details even when no interrupts >>>> + * are in use >>>> + * @chip_resume: function called from core code on resume once per chip; >>>> + * for handling chip details even when no interrupts are >>>> + * in use >>>> * @irq_calc_mask: Optional function to set irq_data.mask for special cases >>>> * @irq_print_chip: optional to print special chip info in show_interrupts >>>> * @irq_request_resources: optional to request resources before calling >>>> @@ -357,6 +365,8 @@ struct irq_chip { >>>> void (*irq_suspend)(struct irq_data *data); >>>> void (*irq_resume)(struct irq_data *data); >>>> void (*irq_pm_shutdown)(struct irq_data *data); >>>> + void (*chip_suspend)(struct irq_chip_generic *gc); >>>> + void (*chip_resume)(struct irq_chip_generic *gc); >>> >>> I really don't want to set a precedent for random (*foo)(*bar) >>> callbacks. >>> >>>> + >>>> + if (ct->chip.chip_suspend) >>>> + ct->chip.chip_suspend(gc); >>> >>> So wouldn't it be the more intuitive solution to make this a callback >>> in the struct gc itself? >> >> Brian can correct me, but his approach is more generic, if there is >> another irqchip driver needing a similar infrastructure, this would be >> already there, and directly usable. > > No it's not directly usable. It's only usable with irq_chip_generic > incarnations. > >> Maybe all we need to is to change the chip_suspend/resume arguments >> to pass a reference to irq_chip instead? > > I just read back on the problem report which was mentioned in the > changelog: > > "It's not a problem with patch 7, exactly, it's a problem with the > irqchip driver which handles the UART interrupt mask (irq-bcm7120-l2.c). > The problem is that with a trimmed down device tree (such as the one > found at arch/arm/boot/dts/bcm7445-bcm97445svmb.dtb), none of the child > interrupts of the 'irq0_intc' node are described -- we don't have device > tree nodes for them yet -- but we still require saving and restoring the > forwarding mask (see 'brcm,int-fwd-mask') in order for the UART > interrupts to continue operating." > > So you are trying to work around a flaw in the device tree by adding > random callbacks to the core kernel? Not quite, you could have your interrupt controller node declared in Device Tree, but have no "interrupts" property referencing it because: - the hardware is just not there, but you inherit a common Device Tree skleten (*.dtsi) - you could have Device Tree overlays which may or may not be loaded as a result of finding expansion boards etc... It just appeared that Brian was specifically testing with something that exposed the problem. -- Florian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/