Date:	Mon, 22 Jun 2015 13:26:01 +0900
From:	Yoshinori Sato <ysato@...rs.sourceforge.jp>
To:	Rob Landley <rob@...dley.net>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Kevin Hilman <khilman@...aro.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Riku Voipio <riku.voipio@...aro.org>,
	Jiri Kosina <jkosina@...e.cz>, Paul Bolle <pebolle@...cali.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Davidlohr Bueso <davidlohr@...com>,
	Richard Weinberger <richard@....at>,
	Zhigang Lu <zlu@...era.com>,
	Vineet Gupta <vgupta@...opsys.com>,
	Richard Kuo <rkuo@...eaurora.org>,
	Max Filippov <jcmvbkbc@...il.com>,
	Pranith Kumar <bobby.prani@...il.com>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH 2/2] Changes to existing files for 0PF FPGA board.

On Sun, 21 Jun 2015 05:13:06 +0900,
Rob Landley wrote:
> 
> On 06/20/2015 03:00 AM, Geert Uytterhoeven wrote:
> > Hi Rob,
> > 
> > On Sat, Jun 20, 2015 at 12:11 AM, Rob Landley <rob@...dley.net> wrote:
> >> On 06/18/2015 02:36 PM, Geert Uytterhoeven wrote:
> >>> On Thu, Jun 18, 2015 at 7:19 PM, Rob Landley <rob@...dley.net> wrote:
> >>>> Changes to existing files to add 0pf j2 board support.
> >>>
> >>> Thanks for your patch!
> >>>
> >>> Like Greg already said, splitting it up in logical parts and providing useful
> >>> patch descriptions would be highly appreciated.
> >>
> >> I actually don't know how to split it up further. The initial port was
> >> done by a series of contractors (in Russia, I think), and then I
> >> inherited it to try to get something releasable. This is the smallest
> >> chunk I could get to actually boot.
> >>
> >> I suppose I could send you the serial driver by itself, and _then_ the
> >> board, but it wouldn't compile if nothing uses it. (Similarly you can't
> >> boot the board without a serial console...)
> > 
> > You don't have to send in a big initial patch that actually boots.
> > For new architecture/SoC/board support, just split it in logical hunks,
> > and submit it in some logical order that always builds.
> > 
> > E.g.:
> >   - SoC core support (arch/sh/),
> >   - Board support (arch/sh/),
> >   - Drivers.
> > 
> > The first two should go in through akpm (sh is orphaned),
> > the rest through the individual subsystem maintainers.
> 
> I'm aware sh is orphaned
> (http://www.openwall.com/lists/musl/2014/02/17/3). I'm trying to do
> something about that.
> 
> I'm not up to maintaining an architecture myself (after the
> kernel.org/doc thing I walked away from kernel stuff for most of a year,
> as you can see I'm a bit out of practice), but I spoke to Yoshinori Sato
> (who used to maintain sh2, and only dropped it when renesas discontinued
> the hardware) and he said he might be interested in returning as a
> co-maintainer.
> 
> (I note that I've been regression testing and fixing sh4 in my
> aboriginal linux project for several years now, although it's been
> quiescent enough on the kernel side the majority of my posts about it
> seem to be qemu issues, from
> https://lists.gnu.org/archive/html/qemu-devel/2010-03/msg00976.html to
> http://comments.gmane.org/gmane.comp.emulators.qemu/294066 . Dealing
> with sh2 is new to me, but it's also my day job these days. :)
> 
> >> (Now the reason _I_ thought you'd reject it had more to do with not
> >> having converted it to device tree yet, and things on that level. But I
> > 
> > Sh is an existing supported architecture, so DT is not a hard requirement.
> 
> Yeah, but new board... And it's the right thing to do.

I think convert DT is best way.

It looks don't use SH compatible peripherals.
I think if it's a SH compatible, it's better to maintain
the platform_device structure.
But use incompatible peripherals (So need new platform_device),
It's difficult to maintain it.

I trying SE7619 target convert to DT. It works fine.
So no problem in 0PF platform DT support.

> > If you would have waited until after the removal of sh, it would be much
> > harder :-) (cfr. h8300, but Sato-san did a great job there, with DT, CCF, ...)
> 
> Indeed he did. We had lunch with him when I was in Japan a couple weeks ago.
> 
> I've got the references I need to do this, just... lots of shoveling on
> a lot of fronts to do right now. (And I mentioned like 3 other things I
> already know I need to fix in the 0/2 message.)
> 
> >> wanted to get it out there so people outside $DAYJOB can test the
> >> hardware. We did a linuxcon japan presentation which lwn.net covered,
> >> and we're getting pokes about "where can I download this", so...)
> > 
> > It's great to hear there's so much interest in this! Let's hope this will
> > attract more actual contributors...
> 
> The "where can I download this" is now the developer tab of 0pf.org by
> the way. And the mailing lists are on lists.nommu.org.
> 
> I'll try to submit an updated patch set in the next couple days.
> 
> Thanks,
> 
> Rob

-- 
Yoshinori Sato
<ysato@...rs.sourceforge.jp>
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