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From: Daniel Palmer <daniel@0x0f.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Bert Vermeulen" <bert@biot.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	"Marc Zyngier" <maz@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"John Crispin" <john@phrozen.org>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"YiFei Zhu" <yifeifz2@illinois.edu>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Mike Rapoport" <rppt@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	DTML <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 4/5] ARM: Add basic support for Airoha EN7523 SoC
Date: Tue, 7 Sep 2021 21:27:46 +0900	[thread overview]
Message-ID: <CAFr9PXn4JXGKSCDNeKMJDPgfezktyfBsTcq8GErt+ROuumDgrg@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a21N8khjyV-f=p28ZogoakhLTrkoPBd6PeXrigba=7-TQ@mail.gmail.com>

Hi Arnd,

On Tue, 7 Sept 2021 at 20:52, Arnd Bergmann <arnd@arndb.de> wrote:
> > Off-topic but related:  Another MediaTek spin off, SigmaStar, seems to
> > have done exactly the same thing. Cortex A53 chip running as a 32bit
> > system to avoid having to fix their software. I'm interested to see if
> > this makes it into arm or arm64. :)
>
> Maybe it's best to just add them to both at the same time? The boot
> loader situation might take a bit to work out, but in theory this should
> be fixable.

I wonder how fixable it would be..

I haven't gotten a board with the chip in question (SSD268G) yet but
from looking at some firmware binaries I can see that even u-boot is a
6 year old 32bit version.
As far as I can tell there's no PSCI, ATF etc that I think would be
expected for an arm64 machine.
I think the broken memory controller is still there so somehow I'd
need to get the heavy barrier to work in arm64. I haven't yet worked
out if that's even possible.
I think they are advertising that it supports up to 2GB of DDR. So
it's a hobbled 64bit capable system with highmem.

Putting most of the DT bits under arm64 even though it's so broken
it'll only ever boot a 32bit kernel makes sense to me.
Better than having lots of arm64 typical stuff like a newer GIC in a
file under arm and confusing everyone that comes across it.

Cheers,

Daniel

WARNING: multiple messages have this Message-ID (diff)
From: Daniel Palmer <daniel@0x0f.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Bert Vermeulen" <bert@biot.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	"Marc Zyngier" <maz@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"John Crispin" <john@phrozen.org>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"YiFei Zhu" <yifeifz2@illinois.edu>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Mike Rapoport" <rppt@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	DTML <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 4/5] ARM: Add basic support for Airoha EN7523 SoC
Date: Tue, 7 Sep 2021 21:27:46 +0900	[thread overview]
Message-ID: <CAFr9PXn4JXGKSCDNeKMJDPgfezktyfBsTcq8GErt+ROuumDgrg@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a21N8khjyV-f=p28ZogoakhLTrkoPBd6PeXrigba=7-TQ@mail.gmail.com>

Hi Arnd,

On Tue, 7 Sept 2021 at 20:52, Arnd Bergmann <arnd@arndb.de> wrote:
> > Off-topic but related:  Another MediaTek spin off, SigmaStar, seems to
> > have done exactly the same thing. Cortex A53 chip running as a 32bit
> > system to avoid having to fix their software. I'm interested to see if
> > this makes it into arm or arm64. :)
>
> Maybe it's best to just add them to both at the same time? The boot
> loader situation might take a bit to work out, but in theory this should
> be fixable.

I wonder how fixable it would be..

I haven't gotten a board with the chip in question (SSD268G) yet but
from looking at some firmware binaries I can see that even u-boot is a
6 year old 32bit version.
As far as I can tell there's no PSCI, ATF etc that I think would be
expected for an arm64 machine.
I think the broken memory controller is still there so somehow I'd
need to get the heavy barrier to work in arm64. I haven't yet worked
out if that's even possible.
I think they are advertising that it supports up to 2GB of DDR. So
it's a hobbled 64bit capable system with highmem.

Putting most of the DT bits under arm64 even though it's so broken
it'll only ever boot a 32bit kernel makes sense to me.
Better than having lots of arm64 typical stuff like a newer GIC in a
file under arm and confusing everyone that comes across it.

Cheers,

Daniel

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-09-07 12:28 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07 10:27 [PATCH v2 0/5] Add support for Airoha EN7523 SoC Bert Vermeulen
2021-09-07 10:27 ` Bert Vermeulen
2021-09-07 10:27 ` [PATCH v2 1/5] dt-bindings: Add vendor prefix for Airoha Bert Vermeulen
2021-09-07 10:27   ` Bert Vermeulen
2021-09-07 11:13   ` Krzysztof Kozlowski
2021-09-07 11:13     ` Krzysztof Kozlowski
2021-09-07 10:27 ` [PATCH v2 2/5] dt-bindings: arm: airoha: Add binding for EN7523 SoC and EVB Bert Vermeulen
2021-09-07 10:27   ` Bert Vermeulen
2021-09-07 10:27 ` [PATCH v2 3/5] ARM: dts: Add basic support for Airoha EN7523 Bert Vermeulen
2021-09-07 10:27   ` Bert Vermeulen
2021-09-07 10:27 ` [PATCH v2 4/5] ARM: Add basic support for Airoha EN7523 SoC Bert Vermeulen
2021-09-07 10:27   ` Bert Vermeulen
2021-09-07 10:48   ` Daniel Palmer
2021-09-07 10:48     ` Daniel Palmer
2021-09-07 11:51     ` Arnd Bergmann
2021-09-07 11:51       ` Arnd Bergmann
2021-09-07 12:27       ` Daniel Palmer [this message]
2021-09-07 12:27         ` Daniel Palmer
2021-09-07 14:11         ` Arnd Bergmann
2021-09-07 14:11           ` Arnd Bergmann
2021-09-07 14:32           ` Daniel Palmer
2021-09-07 14:32             ` Daniel Palmer
2021-09-07 15:22             ` Arnd Bergmann
2021-09-07 15:22               ` Arnd Bergmann
2021-09-07 10:27 ` [PATCH v2 5/5] ARM: multi_v7_defconfig: Add " Bert Vermeulen
2021-09-07 10:27   ` Bert Vermeulen
2021-09-07 10:39   ` Dmitry Osipenko
2021-09-07 10:39     ` Dmitry Osipenko
2021-09-07 10:41     ` Bert Vermeulen
2021-09-07 10:41       ` Bert Vermeulen
2021-09-07 11:03       ` Dmitry Osipenko
2021-09-07 11:03         ` Dmitry Osipenko

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