From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751926AbdATLxQ (ORCPT ); Fri, 20 Jan 2017 06:53:16 -0500 Received: from fllnx210.ext.ti.com ([198.47.19.17]:31289 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751681AbdATLxP (ORCPT ); Fri, 20 Jan 2017 06:53:15 -0500 Subject: Re: [PATCH v2 1/2] ARM: davinci: Allocate extra interrupts To: David Lechner , References: <1484337612-11120-1-git-send-email-david@lechnology.com> <1484337612-11120-2-git-send-email-david@lechnology.com> <95440160-8346-fef8-27d2-fb17c0da38f6@ti.com> <25c0bc60-bb99-9aa5-db56-6299d82db9c1@lechnology.com> CC: Kevin Hilman , From: Sekhar Nori Message-ID: <0bd745dc-df46-0d37-ed18-b419c1cf2e78@ti.com> Date: Fri, 20 Jan 2017 17:20:28 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <25c0bc60-bb99-9aa5-db56-6299d82db9c1@lechnology.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 18 January 2017 10:27 PM, David Lechner wrote: > On 01/18/2017 03:50 AM, Sekhar Nori wrote: >> On Saturday 14 January 2017 01:30 AM, David Lechner wrote: >>> This allocates extra interrupts for mach-davinci. These extra interrupts >>> are need for things like IIO triggers. >> >> I am not really familiar with IIO triggers. Can you give some more >> detail on what fails without this patch? > > A trigger is used to initiate the reading of an iio device. For example, > there is a mechanism for a sysfs trigger. When you write 1 to the sysfs > attribute, it triggers an interrupt that is handled by the iio device. > > Since these triggers use interrupts, you need to allocate spare > interrupts in order to set up the trigger. Otherwise, setting up the > trigger will fail with an error code (I forgot which one exactly) > because all of the allocated irqs have already been assigned to hardware > irqs and are not available. > > Here is where the iio subsytem actually allocates the irq: > http://lxr.free-electrons.com/source/drivers/iio/industrialio-trigger.c#L525 Alright, I will take a look. Do note that this may not get included in the first batch of v4.11 changes I queue. But I promise to come back to it soon afterwards. Thanks, Sekhar