From: Rob Herring <robh@kernel.org>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Khouloud Touil <ktouil@baylibre.com>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Mark Rutland <mark.rutland@arm.com>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
baylibre-upstreaming@groups.io,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
linux-i2c <linux-i2c@vger.kernel.org>
Subject: Re: [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios
Date: Wed, 4 Dec 2019 09:14:24 -0600 [thread overview]
Message-ID: <20191204151424.GA20683@bogus> (raw)
In-Reply-To: <CAMRc=MfVod5ODvsQbVBny1+Yvre1F971uR_DqsvoiYATvUfoXw@mail.gmail.com>
On Fri, Nov 29, 2019 at 09:47:01AM +0100, Bartosz Golaszewski wrote:
> czw., 28 lis 2019 o 14:45 Linus Walleij <linus.walleij@linaro.org> napisał(a):
> >
> > On Tue, Nov 26, 2019 at 4:18 PM Khouloud Touil <ktouil@baylibre.com> wrote:
> >
> > > [Me]
> > >> 4. The code still need to be modified to set the value
> > >> to "1" to assert the line since the gpiolib now handles
> > >> the inversion semantics.
> >
> > > By saying "assert the wp" do you mean enable the write operation or
> > > block it ?
> >
> > Yeah one more layer of confusion, sorry :/
> >
> > By "asserting WP" I mean driving the line to a state where
> > writing to the EEPROM is enabled, i.e. the default state is
> > that the EEPROM is write protected and when you "assert"
> > WP it becomes writable.
> >
> > If you feel the inverse semantics are more intuitive (such that
> > WP comes up asserted and thus write protected), be my
> > guest :D
> >
>
> Ha! I've always assumed that "to assert the write-protect pin" means
> to *protect* the EEPROM from writing. That's why it comes up as
> asserted (logical '1' in the driver) and we need to deassert it (drive
> it low, logical '0' in the driver) to enable writing. This is the
> current behavior and I'd say in this case it's just a matter of very
> explicit statement that this is how it works in the DT binding?
>
> Rob: any thoughts on this?
I agree with you. If it was called write-enable-gpios, then assert would
be to enable writing.
Rob
next prev parent reply other threads:[~2019-12-04 15:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-20 14:20 [PATCH 0/4] at24: move write-protect pin handling to nvmem core Khouloud Touil
2019-11-20 14:20 ` [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios Khouloud Touil
2019-11-22 12:41 ` Linus Walleij
2019-11-22 12:47 ` Bartosz Golaszewski
2019-11-22 12:53 ` Linus Walleij
2019-11-22 13:04 ` Bartosz Golaszewski
2019-11-22 13:46 ` Linus Walleij
[not found] ` <CALL1Z1xpcGyh_f3ooRT+gGApoAnS7YBMd2hUKqnt+pTcAFoeAg@mail.gmail.com>
2019-11-28 13:44 ` Linus Walleij
2019-11-29 8:47 ` Bartosz Golaszewski
2019-12-04 15:14 ` Rob Herring [this message]
2019-11-22 13:10 ` Peter Rosin
2019-11-20 14:20 ` [PATCH 2/4] nvmem: add support for the write-protect pin Khouloud Touil
2019-11-22 12:47 ` Linus Walleij
2019-11-20 14:20 ` [PATCH 3/4] dt-bindings: at24: remove the optional property write-protect-gpios Khouloud Touil
2019-12-04 15:22 ` Rob Herring
2019-11-20 14:20 ` [PATCH 4/4] eeprom: at24: remove the write-protect pin support Khouloud Touil
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