linux-kernel - Re: [RFC PATCH 00/10] Netronix embedded controller driver for Kobo and Tolino ebook readers

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Message-ID: <20200706212848.7e19886b@aktux>
Date:   Mon, 6 Jul 2020 21:28:48 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     Jonathan Neuschäfer <j.neuschaefer@....net>
Cc:     linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Heiko Stuebner <heiko.stuebner@...obroma-systems.com>,
        Stephan Gerhold <stephan@...hold.net>,
        Lubomir Rintel <lkundrak@...sk>,
        Mark Brown <broonie@...nel.org>, allen <allen.chen@....com.tw>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-rtc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Heiko Stuebner <heiko@...ech.de>,
        Josua Mayer <josua.mayer@....eu>
Subject: Re: [RFC PATCH 00/10] Netronix embedded controller driver for Kobo
 and Tolino ebook readers

On Sat, 4 Jul 2020 22:58:08 +0200
Jonathan Neuschäfer <j.neuschaefer@....net> wrote:

> On Tue, Jun 30, 2020 at 10:14:47PM +0200, Andreas Kemnade wrote:
> > On Tue, 30 Jun 2020 09:15:23 +0200
> > Jonathan Neuschäfer <j.neuschaefer@....net> wrote:
> >   
> > > 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.
> > > > 
> > > > I got this.
> > > > 
> > > > [    1.453603] ntxec 0-0043: Netronix embedded controller version f110 detected.
> > > > [   10.723638] ntxec-rtc 21a0000.i2c:embedded-controller@43:rtc: registered as rtc0
> > > > [   10.775276] ntxec-pwm: probe of 21a0000.i2c:embedded-controller@43:pwm failed with error -5    
> > > 
> > > Hmm, -EIO from the PWM driver.
> > >   
> > turing debugging on:  
> 
> (edited for compactness:)
> > [  330.332971] i2c i2c-0: write slave address: addr=0x86   ACK received
> > [  330.334420] i2c i2c-0: write byte: B0=0xA3              ACK received
> > [  330.334790] i2c i2c-0: write byte: B1=0x0               No ACK  
> 
> > [  330.352339] i2c i2c-0: write slave address: addr=0x86   ACK received
> > [  330.362208] i2c i2c-0: write byte: B0=0xA1              ACK received
> > [  330.362479] i2c i2c-0: write byte: B1=0xFF              No ACK  
> 
> > [  330.363112] i2c i2c-0: write slave address: addr=0x86   ACK received
> > [  330.363362] i2c i2c-0: write byte: B0=0xA2              ACK received
> > [  330.363608] i2c i2c-0: write byte: B1=0xFF              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). :/
> 
That is a also my theory.

> 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).
> 
Yes, that can be done separately (after the Tolino Shine 2 HD dtb is
in, I am polishing it right now).

Regards,
Andreas