linux-kernel - Re: [PATCH v3] mfd: syscon: Add Spreadtrum physical regmap bus support

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Date:   Tue, 28 Apr 2020 15:06:21 +0800
From:   Baolin Wang <baolin.wang7@...il.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Mark Brown <broonie@...nel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] mfd: syscon: Add Spreadtrum physical regmap bus support

On Mon, Apr 27, 2020 at 5:05 PM Lee Jones <lee.jones@...aro.org> wrote:
>
> On Mon, 27 Apr 2020, Baolin Wang wrote:
>
> > Hi Arnd and Lee,
> >
> > On Tue, Apr 21, 2020 at 10:13 PM Baolin Wang <baolin.wang7@...il.com> wrote:
> > >
> > > Some platforms such as Spreadtrum platform, define a special method to
> > > update bits of the registers instead of read-modify-write, which means
> > > we should use a physical regmap bus to define the reg_update_bits()
> > > operation instead of the MMIO regmap bus. Thus we can register a new
> > > physical regmap bus into syscon core to support this.
> > >
> > > Signed-off-by: Baolin Wang <baolin.wang7@...il.com>
> >
> > Do you have any comments for this patch? Thanks.
>
> Yes.  I'm not accepting it, sorry.
>
> I'd rather you duplicate the things you need from of_syscon_register()
> in your own driver than taint this one.

Thanks for your comments and I can understand your concern. But we
still want to use the standard syscon APIs in syscon.c, which means we
still need insert an callback or registration or other similar methods
to support vendor specific regmap bus. Otherwise we should invent some
similar syscon APIs in our vendor syscon driver, like
sprd_syscon_regmap_lookup_by_phandle/sprd_syscon_regmap_lookup_by_compatible.

Arnd, what do you think? Thanks.

> > > ---
> > > Changes from v2:
> > >  - Fix building errors without enabling CONFIG_ARCH_SPRD.
> > >
> > > Changes from v1:
> > >  - Add WARN_ONCE() for seting bits and clearing bits at the same time.
> > >  - Remove the Spreadtrum SoC syscon driver, instead moving the regmap_bus
> > >  instance into syscon.c driver.
> > >
> > > Changes from RFC v2:
> > >  - Drop regmap change, which was applied by Mark.
> > >  - Add more information about how to use set/clear.
> > >  - Add checking to ensure the platform is compatible with
> > >  using a new physical regmap bus.
> > >
> > > Changes from RFC v1:
> > >  - Add new helper to registers a physical regmap bus instead of
> > >  using the MMIO bus.
> > > ---
> > >  drivers/mfd/syscon.c | 83 ++++++++++++++++++++++++++++++++++++++++++--
> > >  1 file changed, 81 insertions(+), 2 deletions(-)
>
> --
> Lee Jones [李琼斯]
> Linaro Services Technical Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog



-- 
Baolin Wang