From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [RFC] [PATCH 1/3] OMAP4: Keyboard Controller Support Date: Tue, 11 May 2010 09:41:37 -0700 Message-ID: <20100511164136.GA7396@core.coreip.homeip.net> References: <27F9C60D11D683428E133F85D2BB4A53043D9EE7F5@dlee03.ent.ti.com> <20100421065550.GL4364@core.coreip.homeip.net> <27F9C60D11D683428E133F85D2BB4A53043DFD5320@dlee03.ent.ti.com> <27F9C60D11D683428E133F85D2BB4A53043DFD5323@dlee03.ent.ti.com> <20100511044156.GA21299@core.coreip.homeip.net> <27F9C60D11D683428E133F85D2BB4A53043DFD532E@dlee03.ent.ti.com> <20100511054552.GA1714@core.coreip.homeip.net> <87sk5yebh8.fsf@deeprootsystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pz0-f204.google.com ([209.85.222.204]:59252 "EHLO mail-pz0-f204.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752277Ab0EKQlq (ORCPT ); Tue, 11 May 2010 12:41:46 -0400 Content-Disposition: inline In-Reply-To: <87sk5yebh8.fsf@deeprootsystems.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Kevin Hilman Cc: "Arce, Abraham" , "linux-input@vger.kernel.org" , "linux-omap@vger.kernel.org" On Tue, May 11, 2010 at 07:53:23AM -0700, Kevin Hilman wrote: > Dmitry Torokhov writes: > > > On Tue, May 11, 2010 at 12:03:44AM -0500, Arce, Abraham wrote: > >> Hi again Dmitry, > >> > >> > No worries, although at first I was surprised that Trilok spoke exactly > >> > the same words I did ;) > >> > > >> > >> :) > >> > >> > > > > > + > >> > > > > > +/* Interrupt thread handler thread */ > >> > > > > > + > >> > > > > > +static irqreturn_t omap_keypad_threaded(int irq, void *dev_id) > >> > > > > > +{ > >> > > > > > >> > > > > Why is iti threaded? I fo not see anything that will sleep. > >> > > > >> > > > >> > > It was implemented based on previous comments... > >> > > > >> > > >> > Would you point me to that comment? Like I said, I do not see anything > >> > that would possibly sleep in this routine so you don't need to use > >> > threaded interrupt. > >> > >> http://www.mail-archive.com/linux-omap@vger.kernel.org/msg26352.html > >> > > > > Thanks. > > > > I think Kevin meant "use theaded IRQ, wherever possible" [if we need > > to sleep in interrupt handler]. > > Actually, even interrupts that don't sleep can use threaded IRQs. I > prefer to see threaded IRQs wherever possible. Especially since we're > moving towards a world where all interrupts are run with interrupts > disabled, using threaded IRQs minimizes interrupts-off critical > sections. > I think in this case threaded IRQ would just add unnecessary overhead. There are no scanning delays, just a few register reads and writes. Input core will take some cycles propagating the events but it disables interrupts anyway. Setting up a separate thread and scheduling does not make much sense here. Also I am not sure if arches with large number of interrupts would want to move to all threaded interrupts model. -- Dmitry