From mboxrd@z Thu Jan 1 00:00:00 1970 From: Damien Riegel Subject: Re: [PATCH 2/2] Input: add touchscreen support for TS-4800 Date: Sun, 13 Dec 2015 15:55:57 -0500 Message-ID: <20151213205557.GA4600@localhost> References: <1449763872-572-1-git-send-email-damien.riegel@savoirfairelinux.com> <1449763872-572-2-git-send-email-damien.riegel@savoirfairelinux.com> <20151213045858.GB22780@dtor-ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.savoirfairelinux.com ([208.88.110.44]:43914 "EHLO mail.savoirfairelinux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752317AbbLMU4D (ORCPT ); Sun, 13 Dec 2015 15:56:03 -0500 Content-Disposition: inline In-Reply-To: <20151213045858.GB22780@dtor-ws> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , kernel@savoirfairelinux.com Hi Dmitry On Sat, Dec 12, 2015 at 08:58:58PM -0800, Dmitry Torokhov wrote: > Hi Damien, > > On Thu, Dec 10, 2015 at 11:11:12AM -0500, Damien Riegel wrote: > > On this board, the touchscreen, an ads7843, is not handled directly by > > Linux but by a companion FPGA. This FPGA is memory-mapped and the IP > > design is very similar to the mk712. > > ... > > > + > > + poll_dev = devm_input_allocate_polled_device(&pdev->dev); > > + if (!poll_dev) > > + return -ENOMEM; > > I wonder how useful touchscreen implemented as polling device is. Isn't > there an interrupt line for it? There is an interrupt line between the touchscreen and the FGPA, but not between the FPGA and the SoC. I agree it is a bit peculiar. Hopefully on more recent boards, they changed their design to handle the touchscreen directly with Linux. Thanks, Damien > Thanks. > > -- > Dmitry