Re: [PATCH 01/27] ARM: pxa: remove unused board files

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Dmitry Baryshkov" <dbaryshkov@gmail.com>
Cc: "Richard Purdie" <richard.purdie@linuxfoundation.org>,
	"Arnd Bergmann" <arnd@kernel.org>,
	"Robert Jarzmik" <robert.jarzmik@free.fr>,
	"Daniel Mack" <daniel@zonque.org>,
	"Haojian Zhuang" <haojian.zhuang@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, "Ales Bardorfer" <ales@i-tech.si>,
	"Ales Snuparek" <snuparek@atlas.cz>,
	"Alex Osborne" <ato@meshy.org>,
	"Alex Osborne" <bobofdoom@gmail.com>,
	"Dirk Opfer" <dirk@opfer-online.de>, "Ian Molton" <spyro@f2s.com>,
	"Lennert Buytenhek" <kernel@wantstofly.org>,
	"Marek Vasut" <marek.vasut@gmail.com>,
	"Michael Petchkovsky" <mkpetch@internode.on.net>,
	"Nick Bane" <nick@cecomputing.co.uk>,
	"Paul Parsons" <lost.distance@yahoo.com>,
	"Philipp Zabel" <philipp.zabel@gmail.com>,
	"Sergey Lapin" <slapin@ossfans.org>,
	"Tomas Cech" <sleep_walker@suse.cz>,
	"Linus Walleij" <linusw@kernel.org>,
	"Marc Zyngier" <maz@kernel.org>
Subject: Re: [PATCH 01/27] ARM: pxa: remove unused board files
Date: Sun, 08 Jan 2023 22:05:14 +0100	[thread overview]
Message-ID: <7a57b319-a774-4f97-af06-fe1a637a45ce@app.fastmail.com> (raw)
In-Reply-To: <CALT56yN9aBn+s5rFB1yBdhGtYa6t=c0JeNmy0T=ckh3bNPgh2Q@mail.gmail.com>

On Fri, Jan 6, 2023, at 11:06, Dmitry Baryshkov wrote:
> пт, 6 янв. 2023 г. в 11:47, Arnd Bergmann <arnd@arndb.de>:
>> > Is there any conversion to DT you can easily point at as an example of
>> > the kinds of changes needed?
>>
>> Robert Jarzmik and Daniel Mack worked on the conversion of the
>> PXA platform to DT. Daniel contributed the port for Raumfeld,
>> which should be complete, while Robert worked on more driver
>> conversions and mentioned[1] that he had converted additional
>> boards in the past but did not merge it upstream. They
>> can probably point you to whatever is missing. I would expect
>> the generic PXA drivers (spi, mmc, nand, i2c, audio, fb, gpio,
>> keypad) to  basically work work a correct DT description,
>> while the machine specific drivers (scoop and pcmcia mainly)
>> will need DT support in the driver.
>>
>> In addition, Linus Walleij and Marc Zyngier have both expressed
>> interest in keeping sa1100 (h3600, collie, assabet, jornada720)
>> alive, but those don't have any DT support yet and require
>> much more work. Also note that while you can now build a kernel
>> that includes support for all little-endian ARMv4T and ARMv5
>> machines, StrongARM machine still require a separate kernel
>> build.
>
> I looked into converting collie to use DT several years ago. The major
> problem was not in the StrongARM itself , but rather in the locomo
> (platform-specific ASIC) and PCMCIA. Unfortunately I abandoned that
> work ages ago. RMK didn't seem to be very interested, if I remember
> correclty.

At least locomo and sa1111 are both private to mach-sa1100
now and no longer shared with pxa, so this should get
a little easier. When I had last looking into cleaning up
sa1100, my impression was that the main work would be converting
most of the drivers to use dynamic resources instead of
hardcoded addresses and interrupts. Looking at locomo again,
my feeling is that this could remain largely unchanged,
as the locomo downstream drivers (led, keyboard, lcd)
are already abstracted enough and locomo itself can
just be an mfd or soc driver.

> I suspect that the platforms might need to be rebootstrapped from the
> ground up. This sounds like a fun project for the next Connect demo :D
>
> BTW: collie is also supported by the qemu (in fact at some point I
> mostly used qemu for debugging collie). I don't think that the LCD
> emulation works, but the rest should be mostly good.

Good to know about the LCD. The qemu support was clearly a
strong reason for keeping this machine vs the others.

     Arnd