Re: [PATCH 3/5] i2c: riic: Add RZ/G2L support

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: "Biju Das" <biju.das.jz@bp.renesas.com>,
	"Chris Brandt" <chris.brandt@renesas.com>,
	"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Jarkko Nikula" <jarkko.nikula@linux.intel.com>,
	"Jean Delvare" <jdelvare@suse.de>,
	"Khalil Blaiech" <kblaiech@mellanox.com>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
	"Bence Csókás" <bence98@sch.bme.hu>,
	"Yicong Yang" <yangyicong@hisilicon.com>,
	"Mike Rapoport" <rppt@kernel.org>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Linux I2C" <linux-i2c@vger.kernel.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Chris Paterson" <Chris.Paterson2@renesas.com>,
	"Biju Das" <biju.das@bp.renesas.com>,
	"Prabhakar Mahadev Lad" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH 3/5] i2c: riic: Add RZ/G2L support
Date: Mon, 14 Jun 2021 15:38:45 +0200	[thread overview]
Message-ID: <CAMuHMdX_-93MGi9X-m8PdMgjWDp=azP0mN+M7ReyokDqEbTVBQ@mail.gmail.com> (raw)
In-Reply-To: <67e00c18b71875a0aaa7a8a02b2b0507f5d7a575.camel@pengutronix.de>

Hi Philipp,

On Mon, Jun 14, 2021 at 3:27 PM Philipp Zabel <p.zabel@pengutronix.de> wrote:
> On Fri, 2021-06-11 at 17:56 +0100, Biju Das wrote:
> > RZ/G2L i2c controller is compatible with RZ/A i2c controller.
> > By default IP is in reset state, so need to perform release
> > reset before accessing any register.
> >
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > ---
> >  drivers/i2c/busses/Kconfig    |  1 +
> >  drivers/i2c/busses/i2c-riic.c | 21 +++++++++++++++++++++
> >  2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> > index 281a65d9b44b..5da09288b461 100644
> > --- a/drivers/i2c/busses/Kconfig
> > +++ b/drivers/i2c/busses/Kconfig
> > @@ -941,6 +941,7 @@ config I2C_QUP
> >  config I2C_RIIC
> >       tristate "Renesas RIIC adapter"
> >       depends on ARCH_RENESAS || COMPILE_TEST
> > +     select RESET_CONTROLLER
>
> There's no need for this. The reset API defines inline stubs so this can
> be compiled without RESET_CONTROLLER enabled.

AFAIK, the issue is that RIIC on RZ/G2L requires reset support,
so it must be enabled when building a kernel for RZ/G2L.
As RZ/A does not need or use it, and may run from SRAM, I'd like to
leave it disabled when building a kernel not including RZ/G2L support.

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