linux-kernel - Re: [PATCH v1] i2c: npcm7xx: Support changing bus speed using debugfs.

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Message-ID: <CAHp75Vc3Bw-dTpEmpeUpB4n5-8-xGPx+jm_HkB5Pj6Qr8U=CAw@mail.gmail.com>
Date:   Thu, 1 Oct 2020 18:40:04 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Tali Perry <tali.perry1@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>, Alex Qiu <xqiu@...gle.com>,
        Kun Yi <kunyi@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Avi Fishman <avifishman70@...il.com>,
        Joel Stanley <joel@....id.au>,
        Tomer Maimon <tmaimon77@...il.com>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] i2c: npcm7xx: Support changing bus speed using debugfs.

On Thu, Oct 1, 2020 at 8:34 AM Tali Perry <tali.perry1@...il.com> wrote:
> On Wed, Sep 30, 2020 at 12:31 PM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> >
> > On Wed, Sep 30, 2020 at 10:13:42AM +0300, Tali Perry wrote:
> > > Systems that can dinamically add and remove slave devices
> >
> > dynamically
> >
> > > often need to change the bus speed in runtime.
> >
> > > This patch exposes the bus frequency to the user.
> >
> > Expose the bus frequency to the user.
> >
> > > This feature can also be used for test automation.
> >
> > In general I think that DT overlays or so should be user rather than this.
> > If we allow to change bus speed settings for debugging purposes it might make
> > sense to do this on framework level for all drivers which support that (via
> > additional callback or so).
>
> Do you mean adding something like this:

Nope. I meant to use DT description for that. I²C core should cope
with DT already.
I do not understand why you need special nodes for that rather than DT
overlay which will change the speed for you.

-- 
With Best Regards,
Andy Shevchenko