linux-kernel - Re: [PATCH 1/2] mfd: syscon: Support physical regmap bus

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Date:   Fri, 24 Apr 2020 09:32:55 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Baolin Wang <baolin.wang7@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Lyra Zhang <zhang.lyra@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mfd: syscon: Support physical regmap bus

On Fri, 24 Apr 2020, Arnd Bergmann wrote:

> On Fri, Apr 24, 2020 at 10:11 AM Lee Jones <lee.jones@...aro.org> wrote:
> > On Fri, 17 Apr 2020, Baolin Wang wrote:
> > > @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
> > >       syscon_config.val_bits = reg_io_width * 8;
> > >       syscon_config.max_register = resource_size(&res) - reg_io_width;
> > >
> > > -     regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > > +      /*
> > > +       * The Spreadtrum syscon need register a real physical regmap bus
> > > +       * with new atomic bits updating operation instead of using
> > > +       * read-modify-write.
> > > +       */
> > > +     if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> > > +         of_device_is_compatible(np, "sprd,atomic-syscon") &&
> >
> > Please find a more generic way of supporting your use-case.  This is a
> > generic driver, and as such I am vehemently against adding any sort of
> > vendor specific code in here.
> 
> I suggested doing it this way, as all alternatives seemed worse than this.

If we're using a registration function (could probably be swapped out
for or accompanied by a Device Tree property) anyway, then why conduct
the vendor platform checks?

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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