Re: dma_declare_coherent_memory and SuperH

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Daniel Palmer <daniel@0x0f.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	Christoph Hellwig <hch@lst.de>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	Linux-sh list <linux-sh@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: dma_declare_coherent_memory and SuperH
Date: Mon, 28 Jun 2021 12:00:45 +0200	[thread overview]
Message-ID: <CAMuHMdU_O3-qgCF3TStdE3Jp2gD6kqhwK9kSECnBeJGB7aNVAA@mail.gmail.com> (raw)
In-Reply-To: <CAFr9PXnuFWFy-3mUAo63aiP5qXmD9ULycWVn=_YG96ReohJAjg@mail.gmail.com>

Hi Daniel,

On Mon, Jun 28, 2021 at 11:30 AM Daniel Palmer <daniel@0x0f.com> wrote:
> On Mon, 28 Jun 2021 at 17:57, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > There is an unmerged patch set by Yoshinori Sato that adds device tree support for SH.
> >
> > But it does not include support for SH7724 yet, only for SH775[01]
> > (note to myself: still have to try it on my landisk).
>
> I have some landisks. Is there a sane u-boot for them? I think mine
> still have the hacked up lilo thing.

I believe Sato-san has one for the new landisks.
Mine is also using the hacked up lilo, with kexec to boot into a modern
kernel.  Unfortunately kexec is broken upstream (since ages), so I cannot
kexec from a modern kernel to a modern kernel.

> > Fortunately most core devices on SH7724 and Ecovec should already
> > have DT support in their drivers. The main missing pieces are
> > interrupt and clock support.
>
> This sounds like a fun project. I'm not sure if I could manage it
> without the Hitachi/Renesas debugging dongle though.

Should be doable with earlycon.

> Anyhow, it would be a shame to remove the ecovec just because it
> doesn't have DT as it pretty much fully works with a few small patches
> to fix some bit rot like ethernet and the LCD not working.

Yeah, I agree the Ecovec24 (and the SH7722-based Migo-R) should be
kept alive.

> I sent a patch a few years ago for the ethernet and never got a response. :(

You mean "[PATCH] SH: Add dma mask for sh_eth on ecovec24."[1]?
Do you still need that patch? Probably this was fixed in the core
core, after the
initial dma_mask breakage.

[1] https://lore.kernel.org/linux-sh/20181203122323.765-1-daniel@0x0f.com/

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds