From: Marc Zyngier <marc.zyngier@arm.com>
To: Mason <slash.tmp@free.fr>,
Lennart Sorensen <lsorense@csclub.uwaterloo.ca>,
Sebastian Frias <sf84@laposte.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Mans Rullgard <mans@mansr.com>
Subject: Re: Using irq-crossbar.c
Date: Mon, 13 Jun 2016 16:57:41 +0100 [thread overview]
Message-ID: <575ED7F5.50701@arm.com> (raw)
In-Reply-To: <575ED623.1070902@free.fr>
On 13/06/16 16:49, Mason wrote:
> On 13/06/2016 17:42, Lennart Sorensen wrote:
>> On Mon, Jun 13, 2016 at 04:57:13PM +0200, Sebastian Frias wrote:
>>> Actually we have 128 inputs and 24 outputs, the 24 outputs go straight to the GIC.
>>> The HW block is a many-to-many router.
>>> There are 128 32bit registers which specify, for each of the corresponding 128 inputs, to which of the 24 outputs it would be routed to.
>>>
>>> There are 4 32bit registers that can show the RAW status of the 128 inputs, but they do not latch on the inputs.
>>> That's why our understanding is that on Linux terms it is not an interrupt controller, but just a many-to-many mux, the only real interrupt-controller (where one can set if the line is active high or low for example) is the GIC.
>>
>> Well that does just sound like a mux. But that does mean you either
>> can't use more than 24 inputs at once, or you will be sharing interrupts.
>>
>> I really hate shared interrupts so I would never design something that
>> way, but it is simpler.
>
> If I am not mistaken, the Cortex A9 MPCore GIC has 32 inputs.
Up to 224 SPIs actually, plus 16 PPIs.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2016-06-13 15:57 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-10 15:37 Using irq-crossbar.c Sebastian Frias
2016-06-10 16:05 ` Marc Zyngier
2016-06-10 19:36 ` Mason
2016-06-11 9:58 ` Marc Zyngier
2016-06-11 15:37 ` Mason
2016-06-12 10:00 ` Marc Zyngier
2016-06-12 13:50 ` Mason
2016-06-13 7:58 ` Marc Zyngier
2016-06-13 14:04 ` Lennart Sorensen
2016-06-13 14:57 ` Sebastian Frias
2016-06-13 15:42 ` Lennart Sorensen
2016-06-13 15:49 ` Mason
2016-06-13 15:57 ` Marc Zyngier [this message]
2016-06-13 17:55 ` Lennart Sorensen
2016-06-13 15:15 ` Sebastian Frias
2016-06-13 16:26 ` Marc Zyngier
2016-06-13 15:46 ` Sebastian Frias
2016-06-13 16:24 ` Marc Zyngier
2016-06-14 16:37 ` Sebastian Frias
2016-06-14 16:39 ` Sebastian Frias
2016-06-16 12:39 ` Sebastian Frias
2016-06-21 10:18 ` Marc Zyngier
2016-06-21 11:03 ` Sebastian Frias
2016-06-21 12:41 ` Marc Zyngier
2016-06-21 15:29 ` Sebastian Frias
2016-06-13 17:59 ` Lennart Sorensen
2016-06-10 16:06 ` Lennart Sorensen
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