-----Original Message-----
From: linux-input-owner@vger.kernel.org [mailto:linux-input-owner@vger.kernel.org] On Behalf Of Tirdea, Irina
Sent: 08 June, 2015 17:29
To: Dmitry Torokhov
Cc: Bastien Nocera; Mark Rutland; linux-input@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: RE: [PATCH 8/9] input: goodix: add support for ESD

quoted

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
Sent: 05 June, 2015 19:46
To: Tirdea, Irina
Cc: Bastien Nocera; Mark Rutland; linux-input@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.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:

quoted

quoted

-----Original Message-----
From: Bastien Nocera [mailto:hadess@hadess.net]
Sent: 04 June, 2015 15:58
To: Tirdea, Irina
Cc: Mark Rutland; Dmitry Torokhov; linux-input@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.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:

quoted

quoted

-----Original Message-----
From: linux-input-owner@vger.kernel.org [mailto:
linux-input-owner@vger.kernel.org] On Behalf Of Mark Rutland
Sent: 28 May, 2015 16:24
To: Tirdea, Irina
Cc: Dmitry Torokhov; Bastien Nocera; linux-input@vger.kernel.org;
devicetree@vger.kernel.org; linux-kernel@vger.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:

quoted

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 <redacted>
---
 .../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

quoted

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.

quoted

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.

Hi Mark, Dmitry,

We have been experimenting with the ESD property exported through sysfs
and found it difficult to use. We are testing this on Android tablets which
do not provide userspace code customized for each subvariant of the same
platform. So the only way for us to set specific parameters for each subvariant
is to specify this in ACPI or DT. 

I could keep the sysfs interface that exports the esd_timeout attribute, but
initialize its value to what ACPI/DT provides. As I mentioned before, I could
separate the esd enabling from the actual timeout if that makes more sense.

What do you think?

Thanks,
Irina

Thanks,
Irina

quoted

Thanks.

--
Dmitry

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