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From: Arnd Bergmann <arnd@arndb.de>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: "Jason Cooper" <jason@lakedaemon.net>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Tim Harvey" <tharvey@gateworks.com>,
	"Krzysztof Hałasa" <khalasa@piap.pl>,
	"Olof Johansson" <olof@lixom.net>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Imre Kaloz" <kaloz@openwrt.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 04/17 v1] irqchip: Add driver for IXP4xx
Date: Mon, 18 Feb 2019 10:40:47 +0100
Message-ID: <CAK8P3a1Y2kLeDYKGMGpuLk8rxUxFwuPvjMRoLj-c2a8Bnwi56w@mail.gmail.com> (raw)
In-Reply-To: <CACRpkdYuvZEPzmeKo552g4DR3wxQZtw24jX3ONbmdoD_6bUSPw@mail.gmail.com>

On Mon, Feb 18, 2019 at 8:17 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Mon, Feb 18, 2019 at 8:06 AM Krzysztof Hałasa <khalasa@piap.pl> wrote:
> > Marc Zyngier <marc.zyngier@arm.com> writes:
> >
> > > It's spelled BE32! ;-) I vaguely remember doing some of that on vulcan,
> > > but that's a decade ago, and I've paged it out... ;-)
> >
> > Right. It's also called value-preserving (where the "value" must 32-bit
> > and aligned on 32-bit boundary) or (double) word invariant.
> >
> > Since most of these accesses are natural 32-bit registers and (almost)
> > none are ASCII/byte-style, it makes sense. IIRC the PCI has its own
> > rules, though.
>
> IIUC PCI should always be LE and readl() writel() always read/write
> in LE. But I see PCI on the IXP4xx is a special history so I am going to
> experience it in all its glory now that I start looking at it.

I found a document that explains some of the more obscure details
of this chip (among a lot of the general concepts), in particular how
you can configure memory regions as either BE, LE-data-coherent or
LE-address-coherent, and the byte swap on PCI depending on that:

https://www.intel.com/content/www/us/en/intelligent-systems/previous-generation/ixp4xx-ixc1100-big-endian-little-endian-modes-app-note.html

      Arnd

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Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-03 21:41 [PATCH 00/17 v1] ARM: ixp4xx: Modernize and DT support Linus Walleij
2019-02-03 21:41 ` [PATCH 01/17 v1] ARM: ixp4xx: Convert to MULTI_IRQ_HANDLER Linus Walleij
2019-02-03 21:41 ` [PATCH 02/17 v1] ARM: ixp4xx: Pass IRQ resource to beeper Linus Walleij
2019-02-03 21:41 ` [PATCH 03/17 v1] ARM: ixp4xx: Convert to SPARSE_IRQ Linus Walleij
2019-02-03 21:41 ` [PATCH 04/17 v1] irqchip: Add driver for IXP4xx Linus Walleij
2019-02-11 15:30   ` Marc Zyngier
2019-02-11 20:58     ` Linus Walleij
2019-02-11 22:11       ` Marc Zyngier
2019-02-18  7:06         ` khalasa
2019-02-18  7:16           ` Linus Walleij
2019-02-18  7:35             ` khalasa
2019-02-18  9:40             ` Arnd Bergmann [this message]
2019-02-18 12:03               ` khalasa
2019-02-18 12:44                 ` Arnd Bergmann
2019-02-19  6:51                   ` khalasa
2019-02-19  9:46                     ` Arnd Bergmann
2019-02-20  7:35                       ` khalasa
2019-02-18  9:18         ` Arnd Bergmann
2019-02-03 21:41 ` [PATCH 05/17 v1] gpio: ixp4xx: Add driver for the IXP4xx GPIO Linus Walleij
2019-02-06 16:03   ` Bartosz Golaszewski
2019-02-21  8:50     ` Linus Walleij
2019-02-03 21:41 ` [PATCH 06/17 v1] ARM: ixp4xx: Switch to use new IRQ+GPIO drivers Linus Walleij
2019-02-03 21:41 ` [PATCH 07/17 v1] clocksource/drivers/ixp4xx: Add driver Linus Walleij
2019-02-03 21:41 ` [PATCH 08/17 v1] ARM: ixp4xx: Switch to use new timer driver Linus Walleij
2019-02-03 21:41 ` [PATCH 09/17 v1] irqchip: ixp4xx: Add DT bindings Linus Walleij
2019-02-18 21:25   ` Rob Herring
2019-02-03 21:41 ` [PATCH 10/17 v1] irqchip: ixp4xx: Add OF initialization support Linus Walleij
2019-02-03 21:41 ` [PATCH 11/17 v1] clocksource/drivers/ixp4xx: Add DT bindings Linus Walleij
2019-02-18 21:26   ` Rob Herring
2019-02-18 22:10     ` Daniel Lezcano
2019-02-03 21:42 ` [PATCH 12/17 v1] clocksource/drivers/ixp4xx: Add OF initialization support Linus Walleij
2019-02-11 11:26   ` Daniel Lezcano
2019-02-03 21:42 ` [PATCH 13/17 v1] gpio: ixp4xx: Add DT bindings Linus Walleij
2019-02-06 16:05   ` Bartosz Golaszewski
2019-02-18 21:27   ` Rob Herring
2019-02-03 21:42 ` [PATCH 14/17 v1] gpio: ixp4xx: Add OF probing support Linus Walleij
2019-02-06 16:13   ` Bartosz Golaszewski
2019-02-21  8:55     ` Linus Walleij
2019-02-03 21:42 ` [PATCH 15/17 v1] ARM: ixp4xx: Add DT bindings Linus Walleij
2019-02-04 15:16   ` Rob Herring
2019-02-08 19:37     ` Linus Walleij
2019-02-03 21:42 ` [PATCH 16/17 v1] ARM: ixp4xx: Add device tree boot support Linus Walleij
2019-02-03 21:42 ` [PATCH 17/17 v1] RFC: ARM: dts: Add some initial IXP4xx device trees Linus Walleij

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