From: Scott Wood <scottwood@freescale.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Purcareata Bogdan <b43198@freescale.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Andreas Mohr <andi@lisas.de>
Subject: Re: [RFC] PPC: MPIC: necessary readback after EOI?
Date: Wed, 7 Jan 2015 11:04:43 -0600 [thread overview]
Message-ID: <1420650283.4961.52.camel@freescale.com> (raw)
In-Reply-To: <1420641876.5830.32.camel@kernel.crashing.org>
On Wed, 2015-01-07 at 15:44 +0100, Benjamin Herrenschmidt wrote:
> On Mon, 2015-01-05 at 12:10 -0600, Scott Wood wrote:
> > It would have been nice if a code comment explained why it was doing the
> > readback... I don't see any particular need to wait for EOI completion
> > here (unlike when masking).
>
> The EOI is what causes the MPIC to drop it's EE output to the CPU, if the
> EOI is processed too slowly & asynchronously (posted write + 33Mhz MPIC)
> we observe cases of spurrious interrupts. We had some macs basically getting
> a spurrious irq for every MPIC interrupts...
Shouldn't reading INTACK be what causes the MPIC to drop its EE output?
-Scott
WARNING: multiple messages have this Message-ID (diff)
From: Scott Wood <scottwood@freescale.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: <linuxppc-dev@lists.ozlabs.org>,
Purcareata Bogdan <b43198@freescale.com>,
<linux-kernel@vger.kernel.org>, Andreas Mohr <andi@lisas.de>
Subject: Re: [RFC] PPC: MPIC: necessary readback after EOI?
Date: Wed, 7 Jan 2015 11:04:43 -0600 [thread overview]
Message-ID: <1420650283.4961.52.camel@freescale.com> (raw)
In-Reply-To: <1420641876.5830.32.camel@kernel.crashing.org>
On Wed, 2015-01-07 at 15:44 +0100, Benjamin Herrenschmidt wrote:
> On Mon, 2015-01-05 at 12:10 -0600, Scott Wood wrote:
> > It would have been nice if a code comment explained why it was doing the
> > readback... I don't see any particular need to wait for EOI completion
> > here (unlike when masking).
>
> The EOI is what causes the MPIC to drop it's EE output to the CPU, if the
> EOI is processed too slowly & asynchronously (posted write + 33Mhz MPIC)
> we observe cases of spurrious interrupts. We had some macs basically getting
> a spurrious irq for every MPIC interrupts...
Shouldn't reading INTACK be what causes the MPIC to drop its EE output?
-Scott
next prev parent reply other threads:[~2015-01-07 17:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-05 14:14 [RFC] PPC: MPIC: necessary readback after EOI? Purcareata Bogdan
2015-01-05 14:14 ` Purcareata Bogdan
2015-01-05 17:46 ` Andreas Mohr
2015-01-05 17:46 ` Andreas Mohr
2015-01-05 18:10 ` Scott Wood
2015-01-05 18:10 ` Scott Wood
2015-01-05 18:43 ` Andreas Mohr
2015-01-05 18:43 ` Andreas Mohr
2015-01-07 2:56 ` Scott Wood
2015-01-07 2:56 ` Scott Wood
2015-01-07 14:44 ` Benjamin Herrenschmidt
2015-01-07 14:44 ` Benjamin Herrenschmidt
2015-01-07 17:04 ` Scott Wood [this message]
2015-01-07 17:04 ` Scott Wood
2015-01-08 19:17 ` Benjamin Herrenschmidt
2015-01-08 19:17 ` Benjamin Herrenschmidt
2015-01-07 14:43 ` Benjamin Herrenschmidt
2015-01-07 14:43 ` Benjamin Herrenschmidt
2015-01-07 14:40 ` Benjamin Herrenschmidt
2015-01-08 0:49 ` Segher Boessenkool
2015-01-08 0:49 ` Segher Boessenkool
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