From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH V6 2/9] genirq: Look-up trigger type if not specified by caller Date: Mon, 13 Jun 2016 12:59:57 +0100 Message-ID: <575EA03D.5070706@arm.com> References: <1465312354-27778-1-git-send-email-jonathanh@nvidia.com> <1465312354-27778-3-git-send-email-jonathanh@nvidia.com> <575E8E29.3090808@arm.com> <575E9457.8010100@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <575E9457.8010100-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jon Hunter , Thomas Gleixner , Jason Cooper Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Stephen Warren , Thierry Reding , Kevin Hilman , Geert Uytterhoeven , Grygorii Strashko , Lars-Peter Clausen , Linus Walleij , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On 13/06/16 12:09, Jon Hunter wrote: > > On 13/06/16 11:42, Marc Zyngier wrote: >> On 07/06/16 16:12, Jon Hunter wrote: >>> For some devices the IRQ trigger type for a device is read from >>> firmware, such as device-tree. The IRQ trigger type is typically read >>> when the mapping for IRQ is created, which is before the IRQ is >>> requested. Hence, the IRQ trigger type is programmed when mapping the >>> IRQ and not when requesting the IRQ. >>> >>> Although this works for most cases, in order to support IRQ chips which >>> require runtime power management, which may not be accessible prior >>> to requesting the IRQ, it is desirable to look-up the IRQ trigger type >>> when it is requested. Therefore, if the IRQ trigger type is not >>> specified when __setup_irq() is called, look-up the saved IRQ trigger >>> type. This will allow us to defer the programming of the trigger type >>> from when the IRQ is mapped to when it is actually requested. >>> >>> Signed-off-by: Jon Hunter >>> Reviewed-by: Marc Zyngier >>> --- >>> kernel/irq/manage.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c >>> index ef0bc02c3a70..eaedeb74b49d 100644 >>> --- a/kernel/irq/manage.c >>> +++ b/kernel/irq/manage.c >>> @@ -1117,6 +1117,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) >>> new->irq = irq; >>> >>> /* >>> + * If the trigger type is not specified by the caller, >>> + * then use the default for this interrupt. >>> + */ >>> + if (!(new->flags & IRQF_TRIGGER_MASK)) >>> + new->flags |= irqd_get_trigger_type(&desc->irq_data); >>> + >>> + /* >>> * Check whether the interrupt nests into another interrupt >>> * thread. >>> */ >>> >> >> I've added the following patch to the queue, in order to deal with >> percpu interrupts that were not handled by this patch: >> >> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c >> index f8fd1fb..00cfc85 100644 >> --- a/kernel/irq/manage.c >> +++ b/kernel/irq/manage.c >> @@ -1751,7 +1751,14 @@ void enable_percpu_irq(unsigned int irq, unsigned int type) >> if (!desc) >> return; >> >> + /* >> + * If the trigger type is not specified by the caller, then >> + * use the default for this interrupt. >> + */ >> type &= IRQ_TYPE_SENSE_MASK; >> + if (type == IRQ_TYPE_NONE) >> + type = irqd_get_trigger_type(&desc->irq_data); >> + > > I am wondering if you need this here because now __setup_irq(), called > by request_percpu_irq(), will actually look-up the saved type even for a > percpu-irq. So shouldn't this already be handled? Or am I missing something? You are overlooking the fact that the configuration registers are themselves per-CPU, which means that __setup_irq() will only configure the interrupt on the CPU it runs on. And you can't even tell which one, since you are in a preemptible context. Does it make more sense? M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html