From: Wolfram Sang <wsa@the-dreams.de>
To: Tomasz Figa <tfiga@chromium.org>
Cc: Bibby Hsieh <bibby.hsieh@mediatek.com>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
linux-i2c <linux-i2c@vger.kernel.org>,
Nicolas Boichat <drinkcat@chromium.org>,
srv_heupstream <srv_heupstream@mediatek.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-devicetree <devicetree@vger.kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH v12 1/2] dt-binding: i2c: add bus-supply property
Date: Tue, 24 Mar 2020 11:34:48 +0100 [thread overview]
Message-ID: <20200324103448.GE1134@ninjato> (raw)
In-Reply-To: <CAAFQd5ANJcReHD_n0LorS+bjE8Cn_W-kY5LNgGG+L+jMmywYfA@mail.gmail.com>
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> > > +- bus-supply
> > > + phandle to the regulator that provides power to i2c.
> >
> > I think this is not clear enough. I assume it means the regulator for
> > driving SCL/SDA? In the coverletter you mention also an EEPROM. In your
> > case, this is driven by the same regulator? I am skeptical we can
> > abstract it like this because I2C devices could be driven by various
> > regulators in the system, so there couldn't be one "bus regulator". The
> > regulator for the EEPROM should be described in the EEPROM node. So,
> > this "bus supply" is only for driving SCL/SDA?
>
> In our case the bus-supply regulator drives the voltage rail to which
> SCL/SDA are pulled up and there is an EEPROM on the bus, powered by
> yet another rail. There is also another slave on the bus which uses
> the same regulator as the bus-supply for its own power.
>
> In other words, bus-supply only ensures that SCL and SDA are in a
> usable state. Other consumers need to refer to the regulator in their
> own supplies if they need it for their own power.
>
> Does this answer your questions?
Yes, this was exactly what I was assuming.
So, I think the above documentation should be changed: s|i2c|SCL/SDA|
D'accord?
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next prev parent reply other threads:[~2020-03-24 10:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 3:49 [PATCH v12 0/2] add power control in i2c and at24 Bibby Hsieh
2020-03-06 3:49 ` [PATCH v12 1/2] dt-binding: i2c: add bus-supply property Bibby Hsieh
2020-03-22 13:07 ` Wolfram Sang
2020-03-23 12:18 ` Tomasz Figa
2020-03-24 10:34 ` Wolfram Sang [this message]
2020-04-15 8:49 ` Bibby Hsieh
2020-04-15 18:20 ` Tomasz Figa
2020-03-06 3:49 ` [PATCH v12 2/2] i2c: core: support bus regulator controlling in adapter Bibby Hsieh
2020-03-06 5:09 ` Tomasz Figa
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