linux-kernel - RE: [PATCH 8/9] input: goodix: add support for ESD

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Date:	Mon, 8 Jun 2015 14:28:49 +0000
From:	"Tirdea, Irina" <irina.tirdea@...el.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	Bastien Nocera <hadess@...ess.net>,
	Mark Rutland <mark.rutland@....com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 8/9] input: goodix: add support for ESD



> -----Original Message-----
> From: Dmitry Torokhov [mailto:dmitry.torokhov@...il.com]
> Sent: 05 June, 2015 19:46
> To: Tirdea, Irina
> Cc: Bastien Nocera; Mark Rutland; linux-input@...r.kernel.org; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 8/9] input: goodix: add support for ESD
> 
> On Fri, Jun 05, 2015 at 04:37:49PM +0000, Tirdea, Irina wrote:
> >
> >
> > > -----Original Message-----
> > > From: Bastien Nocera [mailto:hadess@...ess.net]
> > > Sent: 04 June, 2015 15:58
> > > To: Tirdea, Irina
> > > Cc: Mark Rutland; Dmitry Torokhov; linux-input@...r.kernel.org; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org
> > > Subject: Re: [PATCH 8/9] input: goodix: add support for ESD
> > >
> > > On Thu, 2015-05-28 at 14:26 +0000, Tirdea, Irina wrote:
> > > >
> > > > > -----Original Message-----
> > > > > From: linux-input-owner@...r.kernel.org [mailto:
> > > > > linux-input-owner@...r.kernel.org] On Behalf Of Mark Rutland
> > > > > Sent: 28 May, 2015 16:24
> > > > > To: Tirdea, Irina
> > > > > Cc: Dmitry Torokhov; Bastien Nocera; linux-input@...r.kernel.org;
> > > > > devicetree@...r.kernel.org; linux-kernel@...r.kernel.org
> > > > > Subject: Re: [PATCH 8/9] input: goodix: add support for ESD
> > > > >
> > > > > On Thu, May 28, 2015 at 01:47:44PM +0100, Irina Tirdea wrote:
> > > > > > Add ESD (Electrostatic Discharge) protection mechanism.
> > > > > >
> > > > > > The driver enables ESD protection in HW and checks a register
> > > > > > to determine if ESD occurred. If ESD is signalled by the HW,
> > > > > > the driver will reset the device.
> > > > > >
> > > > > > The ESD poll time (in ms) can be set through
> > > > > > esd-recovery-timeout-ms ACPI/DT property. If it is set to 0,
> > > > > > ESD protection is disabled.
> > > > > >
> > > > > > Signed-off-by: Irina Tirdea <irina.tirdea@...el.com>
> > > > > > ---
> > > > > >  .../bindings/input/touchscreen/goodix.txt          |   4 +
> > > > > >  drivers/input/touchscreen/goodix.c                 | 106
> > > > > > ++++++++++++++++++++-
> > > > > >  2 files changed, 106 insertions(+), 4 deletions(-)
> > > > > >
> > > > > > diff --git
> > > > > > a/Documentation/devicetree/bindings/input/touchscreen/goodix.txt
> > > > > b/Documentation/devicetree/bindings/input/touchscreen/goodix.txt
> > > > > > index 9e4ff69..9132ee0 100644
> > > > > > ---
> > > > > > a/Documentation/devicetree/bindings/input/touchscreen/goodix.txt
> > > > > > +++
> > > > > > b/Documentation/devicetree/bindings/input/touchscreen/goodix.txt
> > > > > > @@ -19,6 +19,10 @@ Optional properties:
> > > > > >
> > > > > >   - device-config : device configuration information
> > > > > > (specified as byte
> > > > > >                     array). Maximum size is 240 bytes.
> > > > > > + - esd-recovery-timeout-ms : ESD poll time (in milli seconds)
> > > > > > for the driver to
> > > > > > +                      check if ESD occurred and in that
> > > > > > case reset the
> > > > > > +                      device. ESD is disabled if this
> > > > > > property is not set
> > > > > > +                      or is set to 0.
> > > > >
> > > > > This sounds like software configuration rather than HW description.
> > > > > Is
> > > > > there any reason this needs to be a DT property?
> > > > >
> > > >
> > > > Although this enables a software feature, it depends on the platform
> > > > if electrostatic discharge
> > > > protection should be enabled or not. Some platform designs handle ESD
> > > > better and do not need
> > > > the SW mechanism, so the property can be used to disable it.
> 
> Even though it depends on the platform it describes software function,
> not hardware. Since it is not necessary for starting the device maybe we
> should indeed export it through sysfs and userspace board code should
> activate it as needed?

Sure, I can do it through sysfs.
The only confusing part is that the tsc2005 touchscreen driver uses the
device tree property esd-recovery-timeout-ms.

> 
> I'll leave the decision to DT folks here.
> 

OK. I will keep this version of the esd patch in v2 and wait for an answer
from DT folks so I know exactly how to handle it.

Thanks,
Irina

> Thanks.
> 
> --
> Dmitry
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