From: Thomas Gleixner <tglx@linutronix.de>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Leonard Crestez <leonard.crestez@nxp.com>,
Abel Vesa <abel.vesa@nxp.com>,
Lucas Stach <l.stach@pengutronix.de>,
Mark Rutland <mark.rutland@arm.com>,
Abel Vesa <abelvesa@gmail.com>, Rob Herring <robh+dt@kernel.org>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>, Jacky Bai <ping.bai@nxp.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
dl-linux-imx <linux-imx@nxp.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Carlo Caione <ccaione@baylibre.com>
Subject: Re: [RFC 0/2] Add workaround for core wake-up on IPI for i.MX8MQ
Date: Wed, 12 Jun 2019 09:37:58 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1906120937430.2214@nanos.tec.linutronix.de> (raw)
In-Reply-To: <86ftofgss2.wl-marc.zyngier@arm.com>
On Wed, 12 Jun 2019, Marc Zyngier wrote:
> On Wed, 12 Jun 2019 08:14:16 +0100,
> Thomas Gleixner <tglx@linutronix.de> wrote:
> > On Mon, 10 Jun 2019, Leonard Crestez wrote:
> > > On 6/10/2019 5:08 PM, Marc Zyngier wrote:
> > > > Nobody is talking about performance here. It is strictly about
> > > > correctness, and what I read about this system is that it cannot
> > > > reliably use cpuidle.
> > > My argument was that it's fine if PPIs and LPIs are broken as long as
> > > they're not used:
> > >
> > > * PPIs are only used for local timer which is not used for wakeup.
> >
> > Huch? The timer has to bring the CPU out of idle as any other
> > interrupt.
>
> They use a separate hack for that, pretending that the timer is
> stopped during idle (it isn't), and setup a broadcast timer when
> entering idle. That timer uses an interrupt that can wake-up the
> target CPU, and all is well in the world. Sort of.
>
> Of course, this breaks as PPIs are not only used by the timer, but
> also by a number of other HW bits (PMU, GIC, guest and hypervisor
> timers), and they don't have corresponding hacks to back them up.
Eew.
next prev parent reply other threads:[~2019-06-12 7:37 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-10 12:13 [RFC 0/2] Add workaround for core wake-up on IPI for i.MX8MQ Abel Vesa
2019-06-10 12:13 ` [RFC 1/2] irqchip: irq-imx-gpcv2: Add workaround for i.MX8MQ ERR11171 Abel Vesa
2019-06-10 12:38 ` Leonard Crestez
2019-06-10 13:24 ` Marc Zyngier
2019-06-10 13:38 ` Abel Vesa
2019-06-10 13:51 ` Marc Zyngier
2019-06-10 14:12 ` Abel Vesa
2019-06-10 14:28 ` Marc Zyngier
2019-06-10 12:13 ` [RFC 2/2] arm64: dts: imx8mq: Add idle states and gpcv2 wake_request broken property Abel Vesa
2019-06-10 13:19 ` [RFC 0/2] Add workaround for core wake-up on IPI for i.MX8MQ Mark Rutland
2019-06-10 13:29 ` Abel Vesa
2019-06-10 13:39 ` Marc Zyngier
2019-06-10 13:55 ` Abel Vesa
2019-06-10 14:07 ` Marc Zyngier
2019-06-10 14:32 ` Leonard Crestez
2019-06-10 14:52 ` Marc Zyngier
2019-06-12 7:14 ` Thomas Gleixner
2019-06-12 7:35 ` Marc Zyngier
2019-06-12 7:37 ` Thomas Gleixner [this message]
2019-06-23 11:47 ` Martin Kepplinger
2019-06-28 8:54 ` Abel Vesa
2019-07-02 6:47 ` Martin Kepplinger
2019-07-02 11:33 ` Abel Vesa
2019-07-08 7:54 ` Martin Kepplinger
2019-07-08 12:20 ` Martin Kepplinger
2019-10-30 6:11 ` Martin Kepplinger
2019-10-30 7:33 ` Martin Kepplinger
2019-10-30 8:08 ` Abel Vesa
2019-10-30 8:14 ` Martin Kepplinger
2019-11-04 8:49 ` Martin Kepplinger
2019-11-04 10:35 ` Abel Vesa
2019-11-06 11:59 ` Martin Kepplinger
2019-11-06 22:36 ` Leonard Crestez
2019-11-08 11:21 ` Martin Kepplinger
2019-11-08 11:50 ` Abel Vesa
2019-11-08 14:17 ` Martin Kepplinger
2019-11-11 7:54 ` Abel Vesa
2019-11-25 17:23 ` Martin Kepplinger
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