Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752376AbcDFRpY (ORCPT ); Wed, 6 Apr 2016 13:45:24 -0400 Received: from mail-pf0-f175.google.com ([209.85.192.175]:34652 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751507AbcDFRpW (ORCPT ); Wed, 6 Apr 2016 13:45:22 -0400 Date: Wed, 6 Apr 2016 10:45:12 -0700 From: Dmitry Torokhov To: Nava kishore Manne Cc: Linus Walleij , =?iso-8859-1?Q?Andersson=2C_Bj=F6rn?= , Peng Fan , Linux Input , "linux-kernel@vger.kernel.org" Subject: Re: [LINUX PATCH v2] gpio_keys: Added support to read the IRQ_FLAGS from devicetree Message-ID: <20160406174512.GD38452@dtor-ws> References: <1459763770-2296-1-git-send-email-navam@xilinx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3182 Lines: 80 On Wed, Apr 06, 2016 at 11:32:55AM +0000, Nava kishore Manne wrote: > > -----Original Message----- > > From: Linus Walleij [mailto:linus.walleij@linaro.org] > > Sent: Monday, April 04, 2016 4:38 PM > > To: Nava kishore Manne > > Cc: Dmitry Torokhov; Andersson, Bj?rn; Nava kishore Manne; Peng Fan; > > Linux Input; linux-kernel@vger.kernel.org > > Subject: Re: [LINUX PATCH v2] gpio_keys: Added support to read the > > IRQ_FLAGS from devicetree > > > > On Mon, Apr 4, 2016 at 11:56 AM, Nava kishore Manne > > wrote: > > > > > This patch adds the support to read the IRQ_FLAGS from the device > > > instead of hard code the flags in gpio_keys_setup_key(). > > > > NACK > > > > > sw14 { > > > label = "sw14"; > > > gpios = <&gpio0 12 1>; > > > /* > > > * Triggering Type: > > > * > > > * 1 - edge rising > > > * 2 - edge falling > > > * 4 - level active high > > > * 8 - level active low > > > * > > > */ > > > > You are completely violating the existing GPIO flags from include/dt- > > bindings/gpio/gpio.h > > > > As you will see, for a twocell GPIO flags are already clearly defined for 0,1,2 > > and 3. (Bit 0 & 1). > > > > Further, these IRQ edge/level flags already exist in include/dt- > > bindings/interrupt-controller/irq.h > > but you should not be using those either, because they do not mix with a > > GPIO specifier, it's a bit like oil and water. > > > > The standard GPIO bindings already has > > GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW > > which makes it pretty clear that a GPIO line marked as GPIO_ACTIVE_HIGH > > should trigger either on rising edge or level active high and vice versa. > > > > The only information you could *possibly* lack is whether the IRQ should be > > edge or level triggered. > > > > But level triggered GPIO buttons *does* *not* *make* > > *sense* *at* *all*. > > > > Think about it: > > > > The IRQ line goes level high or low because a user pressed a button with > > his/her thumb. Then that is wired in as a level IRQ. So what are we going to > > do? Wait in the interrupt handler until the user removes his/her thumb? > > > > Level IRQs on GPIOs only makes sense for devices off-chip where you can > > talk to the device and ACK the interrupt, and in this case "talk" does not > > mean wire up a speaker telling the user to remove the thumb from the > > button because we have recieved the interrupt, albeit that would be the > > real-world analogy. > > > > Please tell us what you are actually trying to solve. > > > One of Our gpio-controller was supporting only edge rising interrupts. > For that reason I implementing the below logic to read the interrupt > trigger level from the DT. If it is wrong could you please provide the > pointer to solve this issue? How will you handle key releases if you can only signal key presses? gpio-keys driver needs to be notified about both edges. Thanks. -- Dmitry