From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932496AbdKFQLD (ORCPT ); Mon, 6 Nov 2017 11:11:03 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:47568 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753299AbdKFQLA (ORCPT ); Mon, 6 Nov 2017 11:11:00 -0500 X-Google-Smtp-Source: ABhQp+RIDgchGfmFaejN2V2leDheLQsvqg2d7o4U+JB1jXettRz5wQ6iw1mtQwZX/8mlQOqYSU5lCw== Date: Mon, 06 Nov 2017 08:10:51 -0800 User-Agent: K-9 Mail for Android In-Reply-To: <20171106090630.GF9728@mail.corp.redhat.com> References: <1509418996-25348-1-git-send-email-hl@rock-chips.com> <1509418996-25348-2-git-send-email-hl@rock-chips.com> <20171101220208.gixv6anohp5q4kh2@rob-hp-laptop> <20171106090630.GF9728@mail.corp.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Subject: Re: [PATCH v2 2/2] devicetree: i2c-hid: Add reset property To: Benjamin Tissoires , Rob Herring CC: Lin Huang , jikos@kernel.org, jani.nikula@intel.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, briannorris@chromium.org, devicetree@vger.kernel.org From: Dmitry Torokhov Message-ID: <06A94585-C766-46A9-89CB-44597FE70565@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vA6GB8j1008120 On November 6, 2017 1:06:30 AM PST, Benjamin Tissoires wrote: >Hi Rob, > >On Nov 01 2017 or thereabouts, Rob Herring wrote: >> On Tue, Oct 31, 2017 at 11:03:16AM +0800, Lin Huang wrote: >> > Document a "reset" and "assert-reset-us", it can be used for >> > driver control reset property. And reuse post-power-on-delay-ms >> > for deassert reset delay. >> >> "dt-bindings: input: " for the subject please. >> >> > >> > Signed-off-by: Lin Huang >> > --- >> > Documentation/devicetree/bindings/input/hid-over-i2c.txt | 4 +++- >> > 1 file changed, 3 insertions(+), 1 deletion(-) >> > >> > diff --git >a/Documentation/devicetree/bindings/input/hid-over-i2c.txt >b/Documentation/devicetree/bindings/input/hid-over-i2c.txt >> > index 28e8bd8..6ab0eed 100644 >> > --- a/Documentation/devicetree/bindings/input/hid-over-i2c.txt >> > +++ b/Documentation/devicetree/bindings/input/hid-over-i2c.txt >> > @@ -31,7 +31,9 @@ device-specific compatible properties, which >should be used in addition to the >> > >> > - vdd-supply: phandle of the regulator that provides the supply >voltage. >> > - post-power-on-delay-ms: time required by the device after >enabling its regulators >> > - before it is ready for communication. Must be used with >'vdd-supply'. >> > + or deassert reset pin before it is ready for communication. >> > +- reset: phandle of the gpio that provides for hid reset pin. >> >> The kernel api takes "reset", but the property is "reset-gpios". > >In the same way the generic regulator interface handles vdd-supply, is >there any generic OF handling of reset lines? As far as I can tell, >there are 97 references of reset-gpios in my tree, and I wonder if all >the matching drivers need to rewrite the same code to set the reset >line >on power on/off. > >I am worried because here, 1/2 writes "arbitrary" 0 and 1 to the gpios, >and nothing prevent a manufacturer to invert the required voltages on >the reset lines, meaning there will be a need for a new OF property. 1and 0 are logical high and low here. Gpiod API takes care of converting to the proper polarity. Thanks. -- Dmitry