From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [PATCH 3/6] irqchip: GICv3: Skip LPI deactivation Date: Wed, 12 Aug 2015 16:28:59 +0200 Message-ID: <55CB582B.50007@linaro.org> References: <1436447951-22357-1-git-send-email-marc.zyngier@arm.com> <1436447951-22357-4-git-send-email-marc.zyngier@arm.com> <55C9C39A.3060208@linaro.org> <55CB4B82.9060601@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Christoffer Dall , Jiang Liu , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.cs.columbia.edu" , "kvm@vger.kernel.org" To: Marc Zyngier , Thomas Gleixner , Jason Cooper Return-path: Received: from mail-wi0-f176.google.com ([209.85.212.176]:33795 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750949AbbHLO3o (ORCPT ); Wed, 12 Aug 2015 10:29:44 -0400 Received: by wicne3 with SMTP id ne3so220908038wic.1 for ; Wed, 12 Aug 2015 07:29:43 -0700 (PDT) In-Reply-To: <55CB4B82.9060601@arm.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/12/2015 03:34 PM, Marc Zyngier wrote: > On 11/08/15 10:42, Eric Auger wrote: >> On 07/09/2015 03:19 PM, Marc Zyngier wrote: >>> Contrary to other GICv3 interrupts, LPIs do not have an active state >>> by virtue of being edge-triggered only (they only have a pending state). >>> >>> Given this, there is no point trying to deactivate them, and we can >>> skip the ICC_DIR_EL1 entierely. >>> >>> Signed-off-by: Marc Zyngier >>> --- >>> drivers/irqchip/irq-gic-v3.c | 8 ++++++-- >>> 1 file changed, 6 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c >>> index 49768fc..e02592b 100644 >>> --- a/drivers/irqchip/irq-gic-v3.c >>> +++ b/drivers/irqchip/irq-gic-v3.c >>> @@ -295,10 +295,14 @@ static int gic_irq_get_irqchip_state(struct irq_data *d, >>> >>> static void gic_eoi_irq(struct irq_data *d) >>> { >>> - if (static_key_true(&supports_deactivate)) >>> + if (static_key_true(&supports_deactivate)) { >>> + /* No need to deactivate an LPI */ >>> + if (gic_irq(d) >= 8192) >> In case of EOIMode == 0, we do not call EOI. I can't understand whether >> it is an issue. > > What do you mean? We definitely perform an EOI in both EOImodes... > >> In 4.8.3 Properties of LPI, in 2d note it is written: >> >> "SW must issue a write to EOI to clear the active priorities register, >> hence the CPU interface still requires an active state for LPIs, even >> through this is not necessary within the redistributor" >> >> Eric >>> + return; >>> gic_write_dir(gic_irq(d)); >>> - else >>> + } else { >>> gic_write_eoir(gic_irq(d)); > > ... right here. > > Of am I missing something completely obvious? yes sorry please forget this. I think I meant EOImode == 1 instead and anyway the EOI is done in gic_handle_irq. Apologies Eric > > Thanks, > > M. >