Re: [PATCH v6 00/10] ARM: dts: exynos: Prepare Spring

From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
To: "Doug Anderson" <dianders@chromium.org>,
	"Andreas Färber" <afaerber@suse.de>
Cc: linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Stephan van Schaik <stephan@synkhronix.com>,
	Vincent Palatin <vpalatin@chromium.org>,
	Tomasz Figa <t.figa@samsung.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH v6 00/10] ARM: dts: exynos: Prepare Spring
Date: Thu, 07 Aug 2014 10:40:36 +0200	[thread overview]
Message-ID: <53E33B84.2010108@collabora.co.uk> (raw)
In-Reply-To: <CAD=FV=WFNW_5KZvLMk0kK1JQsdWLeo2kCjpQsFuxKNSnOKzfgw@mail.gmail.com>

Hello,

On 08/04/2014 05:42 PM, Doug Anderson wrote:
> 
> 
>> For the touchpad it seems DT support has landed in the input tree as
>> "atmel,maxtouch". Backporting just that patch does not make it work
>> though. (Tried the rejected pinctrl approach to be on the safe side.)
>> https://code.google.com/p/chromium/issues/detail?id=371114
>> https://patchwork.kernel.org/patch/3976801/
> 
> This is the same work as needed for pit and pi, I believe.  Perhaps
> Javier or Dmitry has this on their todo list?
> 
> 

I posted a couple of patches that allowed me to have the atmel touchpad working
on Peach Pit. I found two issues while testing the driver:

a) The device keycode event capabilities are hardcoded in the downstream Chrome
OS driver while the mainline driver expect these to be defined in the DT. The
property is called "linux,gpio-keymap" since it seems that the actual
implementation is using a set of GPIOs. But this is handled by the firmware
since the kernel just read a status register from the atmel T9 object.

I found the property confusing at first since it didn't have anything to do with
Linux GPIO so posted a patch to add an example to the DT binding doc in order to
make it easier to understand [0].

b) The driver overwrites the edge/level flags parsed by OF core and expects that
the IRQ type will be passed using platform data. The downstream Chrome OS driver
defaults the type to IRQF_TRIGGER_FALLING if this is not provided while the
mainline does not have a default so it's just 0 (IRQ_TYPE_NONE).

This is fixed by reading back the IRQ type from the struct irq_data when parsing
the DT data [1].

The DTS changes to make the atmel touchpad work on Peach Pit were posted in [2].
Changes for Pi were included as well since it should be the same but it was not
tested since I don't have access to that machine, testing will be highly
appreciated.

> 
> -Doug
> 

Thanks a lot and best regards,
Javier

[0]: https://lkml.org/lkml/2014/8/6/584
[1]: https://lkml.org/lkml/2014/8/7/82
[2]: https://lkml.org/lkml/2014/8/6/589