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Date:   Sat, 4 Jul 2020 22:58:08 +0200
From:   Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
To:     Andreas Kemnade <andreas@kemnade.info>
Cc:     Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>,
        linux-kernel@vger.kernel.org, Lee Jones <lee.jones@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Alessandro Zummo <a.zummo@towertech.it>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Heiko Stuebner <heiko.stuebner@theobroma-systems.com>,
        Stephan Gerhold <stephan@gerhold.net>,
        Lubomir Rintel <lkundrak@v3.sk>,
        Mark Brown <broonie@kernel.org>, allen <allen.chen@ite.com.tw>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        devicetree@vger.kernel.org, linux-pwm@vger.kernel.org,
        linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Heiko Stuebner <heiko@sntech.de>,
        Josua Mayer <josua.mayer@jm0.eu>
Subject: Re: [RFC PATCH 00/10] Netronix embedded controller driver for Kobo
 and Tolino ebook readers
Message-ID: <20200704205808.GD2578@latitude>
References: <20200620223915.1311485-1-j.neuschaefer@gmx.net>
 <20200630084051.66feadea@aktux>
 <20200630071523.GA2983@latitude>
 <20200630221447.3e03ae28@aktux>
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On Tue, Jun 30, 2020 at 10:14:47PM +0200, Andreas Kemnade wrote:
> On Tue, 30 Jun 2020 09:15:23 +0200
> Jonathan Neusch=C3=A4fer <j.neuschaefer@gmx.net> wrote:
>=20
> > On Tue, Jun 30, 2020 at 08:40:51AM +0200, Andreas Kemnade wrote:
> > [...]
> > > got a chance to test it on a Tolino Shine 2 HD.
> > > It uses the RTC from the RC5T619 but backlight seems to go via MSP430
> > > EC.
> > >=20
> > > I got this.
> > >=20
> > > [    1.453603] ntxec 0-0043: Netronix embedded controller version f11=
0 detected.
> > > [   10.723638] ntxec-rtc 21a0000.i2c:embedded-controller@43:rtc: regi=
stered as rtc0
> > > [   10.775276] ntxec-pwm: probe of 21a0000.i2c:embedded-controller@43=
:pwm failed with error -5 =20
> >=20
> > Hmm, -EIO from the PWM driver.
> >=20
> turing debugging on:

(edited for compactness:)
> [  330.332971] i2c i2c-0: write slave address: addr=3D0x86   ACK received
> [  330.334420] i2c i2c-0: write byte: B0=3D0xA3              ACK received
> [  330.334790] i2c i2c-0: write byte: B1=3D0x0               No ACK

> [  330.352339] i2c i2c-0: write slave address: addr=3D0x86   ACK received
> [  330.362208] i2c i2c-0: write byte: B0=3D0xA1              ACK received
> [  330.362479] i2c i2c-0: write byte: B1=3D0xFF              No ACK

> [  330.363112] i2c i2c-0: write slave address: addr=3D0x86   ACK received
> [  330.363362] i2c i2c-0: write byte: B0=3D0xA2              ACK received
> [  330.363608] i2c i2c-0: write byte: B1=3D0xFF              No ACK

Hmm, it doesn't ack the writes to 0xA3, 0xA1 and 0xA2, which should
disable the PWM output and then disable the auto-off timer (according to
the vendor kernel).

And you said in your other mail that you can actually toggle the light
with writes to 0xA3, so I suspect a bug in the EC firmware here (which
may have gone unnoticed because the vendor kernel doesn't check if the
i2c transfers succeed). :/

IMHO we should get this driver merged first, and perhaps add a quirk to
deal with the missing ACKs later (unless a better solution is found).


Jonathan

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