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

From: "Jonathan Neuschäfer" <j.neuschaefer@gmx.net>
To: Andreas Kemnade <andreas@kemnade.info>
Cc: "Jonathan Neuschäfer" <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 Kleine-König" <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
Date: Sat, 4 Jul 2020 22:58:08 +0200	[thread overview]
Message-ID: <20200704205808.GD2578@latitude> (raw)
In-Reply-To: <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 Neuschäfer <j.neuschaefer@gmx.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). :/

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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