linux-kernel - Re: [PATCH v5 5/5] arm64: dts: exynos: Add tm2 touchkey node

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Date:   Sun, 8 Jan 2017 14:45:04 +0900
From:   Andi Shyti <andi@...zian.org>
To:     Chanwoo Choi <cwchoi00@...il.com>
Cc:     Andi Shyti <andi@...zian.org>, Andi Shyti <andi.shyti@...sung.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Beomho Seo <beomho.seo@...sung.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-input@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
        Jaechul Lee <jcsing.lee@...sung.com>,
        Jaechul Lee <galaxyra@...il.com>
Subject: Re: [PATCH v5 5/5] arm64: dts: exynos: Add tm2 touchkey node

Hi Chanwoo,

> >> >>> +       touchkey@20 {
> >> >>> +               compatible = "samsung,tm2-touchkey";
> >> >>> +               reg = <0x20>;
> >> >>> +               interrupt-parent = <&gpa3>;
> >> >>> +               interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> >> >>> +               vcc-supply = <&ldo32_reg>;
> >> >>> +               vdd-supply = <&ldo33_reg>;
> >> >>> +       };
> >> >>> +};
> >> >>> +
> >> >>>  &ldo31_reg {
> >> >>>         regulator-name = "TSP_VDD_1.85V_AP";
> >> >>>         regulator-min-microvolt = <1850000>;
> >>
> >> I repiled the touchkey driver against compatible name.
> >> Usually, when developing the device driver, we use the specific h/w name
> >> but in this patch, the touckey dt node uses the h/w board name instead of
> >> original touckhey name.
> >
> > this should be a device specifically done for the tm2 and we are
> > not sure who is the manufacturer of the device. In order to not
> 
> As I knew, this touchkey was made by Cypress semiconductor.
> But, for more correct information, you may try to find it.

The Android Kernel says that this is the cy8cmbr3xxx. I
downloaded the datasheets, but it doesn't have any similarity
with the device. Which means that on tm2 we don't the
cy8cmbr3xxx bot something else that I even doubt comes from
cypress, but I strongly believe it's a dedicated hardware.

Now we have two choices:

1. drop support because we are not 100% sure on the device and
supplier.

2. call it Samsung and provide support anyway as, at the end, it
is a samsung hardware.

With Jaechul we chose option 2.

> > assign the device to the wrong manufacturer, we preferred calling
> > it Samsung as it is in a Samsung device.
> 
> As you mentioned, Samsung made not this touchkey device. It is
> certainly wrong manufacturer. I have not seen to use the h/w board
> name as the peripheral device name.
> 
> I don't prefer to use the inaccurate manufacturer and device name.

Eventually, Jaechul can assign the device to cypress, but the
name has to remain tm2-touchkey. Something like this:

	compatible = "cypress,tm2-touchkey";

What do you think?

Andi