From: "H. Peter Anvin" <hpa-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: Sebastian Andrzej Siewior
<bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: sodaville-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [sodaville] [PATCH 10/15] x86/ioapic: Add OF bindings for IO-APIC
Date: Wed, 12 Jan 2011 09:19:53 -0800 [thread overview]
Message-ID: <4D2DE2B9.2000607@linux.intel.com> (raw)
In-Reply-To: <20110112170707.GA6907-Hfxr4Dq0UpYb1SvskN2V4Q@public.gmane.org>
On 01/12/2011 09:07 AM, Sebastian Andrzej Siewior wrote:
>>
>> I'm confused here. Are there multiple ioapic's described by a single
>> device tree node?
>
> Yes, the CE4100 has two IO-APICs. It looks like the first one is
> responsible for the "legacy devices" (like RTC) and the second one is
> used for the "extra devices" like SPI controller, USB, ... The UART
> however is not on the first IO-APIC but on the second.
>
> Those two IO-APICs are not cascaded. The device tree contains the line
> number of device to the io apic. The kernel computes then interrupt
> number based on gsi_base + line_number where gsi_base is incremented by
> the number of entries[0]. This interrupt number (gsi_base + line) is then
> sent via apic bus to lapic which reports it as the active interrupt
> source.
>
That's normal multiple IOAPIC behavior (and multiple IOAPICs is a common
thing), but why use the same device tree node for both?
-hpa
next prev parent reply other threads:[~2011-01-12 17:19 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1292600033-12271-1-git-send-email-bigeasy@linutronix.de>
[not found] ` <1292600033-12271-1-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2010-12-17 15:33 ` [PATCH 02/15] x86: Add device tree support Sebastian Andrzej Siewior
2010-12-30 8:43 ` Grant Likely
[not found] ` <20101230084311.GD11721-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2010-12-30 21:01 ` Grant Likely
[not found] ` <AANLkTi=EFewaizO=1FLALE0eQPUmaFPfTmgoeF+JRpkt-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-02 0:40 ` H. Peter Anvin
2011-01-03 12:20 ` Sebastian Andrzej Siewior
2011-01-03 18:05 ` [sodaville] " H. Peter Anvin
2010-12-17 15:33 ` [PATCH 03/15] x86/dtb: Add a device tree for CE4100 Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-4-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2010-12-30 8:51 ` Grant Likely
[not found] ` <20101230085122.GE11721-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-03 11:28 ` Sebastian Andrzej Siewior
2011-01-03 17:45 ` Grant Likely
[not found] ` <20110103174500.GC2522-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-05 9:48 ` [PATCH v2 " Sebastian Andrzej Siewior
2011-01-05 10:01 ` [PATCH " Sebastian Andrzej Siewior
2011-01-05 23:20 ` David Gibson
2010-12-17 15:33 ` [PATCH 04/15] x86/dtb: add irq domain abstraction Sebastian Andrzej Siewior
2011-01-11 22:03 ` Grant Likely
[not found] ` <20110111220317.GA2131-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-23 13:06 ` Sebastian Andrzej Siewior
2010-12-17 15:33 ` [PATCH 05/15] x86/dtb: add early parsing of APIC and IO APIC Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-6-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2010-12-30 8:54 ` Grant Likely
2011-01-04 13:23 ` [PATCH v2 " Sebastian Andrzej Siewior
[not found] ` <20110104132302.GB21359-Hfxr4Dq0UpYb1SvskN2V4Q@public.gmane.org>
2011-01-11 22:14 ` Grant Likely
[not found] ` <20110111221401.GB2131-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-18 14:56 ` Sebastian Andrzej Siewior
2010-12-17 15:33 ` [PATCH 06/15] x86/dtb: add support hpet Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-7-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2011-01-11 22:26 ` Grant Likely
2010-12-17 15:33 ` [PATCH 07/15] of: move of_irq_map_pci() into generic code Sebastian Andrzej Siewior
2010-12-17 21:16 ` Benjamin Herrenschmidt
2011-01-04 14:27 ` [PATCH v2 " Sebastian Andrzej Siewior
[not found] ` <20110104142754.GD21359-Hfxr4Dq0UpYb1SvskN2V4Q@public.gmane.org>
2011-01-11 23:27 ` Grant Likely
[not found] ` <20110111232726.GD2131-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-12 18:21 ` Sebastian Andrzej Siewior
2010-12-17 15:33 ` [PATCH 08/15] x86/dtb: add support for PCI devices backed by dtb nodes Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-9-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2011-01-11 23:47 ` Grant Likely
2010-12-17 15:33 ` [PATCH 09/15] x86/dtb: Add generic bus probe Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-10-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2011-01-11 23:48 ` Grant Likely
2010-12-17 15:33 ` [PATCH 10/15] x86/ioapic: Add OF bindings for IO-APIC Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-11-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2011-01-11 23:53 ` Grant Likely
[not found] ` <20110111235353.GG2131-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-12 17:07 ` Sebastian Andrzej Siewior
[not found] ` <20110112170707.GA6907-Hfxr4Dq0UpYb1SvskN2V4Q@public.gmane.org>
2011-01-12 17:19 ` H. Peter Anvin [this message]
[not found] ` <4D2DE2B9.2000607-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2011-01-13 10:38 ` [sodaville] " Sebastian Andrzej Siewior
2010-12-17 15:33 ` [PATCH 12/15] of/address: use propper endianess in get_flags Sebastian Andrzej Siewior
2010-12-30 9:05 ` Grant Likely
2010-12-17 15:33 ` [PATCH 14/15] rtc/cmos: add OF bindings Sebastian Andrzej Siewior
[not found] ` <1292600033-12271-15-git-send-email-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2011-01-12 0:04 ` Grant Likely
[not found] ` <20110112000442.GJ2131-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-01-13 10:50 ` [PATCH v2] " Sebastian Andrzej Siewior
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