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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200428081902.GK3559@dell>
Date:   Tue, 28 Apr 2020 09:19:02 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Baolin Wang <baolin.wang7@...il.com>
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 Tue, 28 Apr 2020, Baolin Wang wrote:

> On Tue, Apr 28, 2020 at 3:14 PM Lee Jones <lee.jones@...aro.org> wrote:
> >
> > On Tue, 28 Apr 2020, Baolin Wang wrote:
> >
> > > 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.
> >
> > So long as the generic driver stays generic.  Providing a registration
> > function sounds cleaner than tainting the code with vendor specifics.
> 
> So seems my V1 patch set [1] was on the direction as you suggested,
> but Arnd did not like that.
> 
> [1]
> https://lore.kernel.org/patchwork/patch/1226161/
> https://lore.kernel.org/patchwork/patch/1226162/

I don't often disagree with Arnd, but in this instance I think a
registration function which allows vendor spin-offs to use the generic
API is better than tainting the generic driver by adding vendor
specific #ifery/code to it.

Your original idea seems more palatable to me.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog