From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:13810 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753571Ab1EYXuP (ORCPT ); Wed, 25 May 2011 19:50:15 -0400 Message-ID: <4DDD95AF.4010004@redhat.com> Date: Wed, 25 May 2011 20:50:07 -0300 From: Mauro Carvalho Chehab MIME-Version: 1.0 To: Laurent Pinchart CC: linux-media@vger.kernel.org, Arnd Bergmann Subject: Re: [GIT PATCH FOR 2.6.40] uvcvideo patches References: <201105150948.24956.laurent.pinchart@ideasonboard.com> <201105260120.54392.laurent.pinchart@ideasonboard.com> <4DDD91F2.5070801@redhat.com> <201105260143.35396.laurent.pinchart@ideasonboard.com> In-Reply-To: <201105260143.35396.laurent.pinchart@ideasonboard.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-ID: Sender: Em 25-05-2011 20:43, Laurent Pinchart escreveu: > Issues arise when devices have floating point registers. And yes, that > happens, I've learnt today about an I2C sensor with floating point registers > (in this specific case it should probably be put in the broken design > category, but it exists :-)). Huh! Yeah, an I2C sensor with FP registers sound weird. We need more details in order to address those. >>> There's an industry trend there, and we need to think about solutions now >>> otherwise we will be left without any way forward when too many devices >>> will be impossible to support from kernelspace (OMAP4 is a good example >>> there, some device drivers require communication with other cores, and >>> the communication API is implemented in userspace). >> >> Needing to go to userspace to allow inter-core communication seems very >> bad. I seriously doubt that this is a trend. It seems more like a >> broken-by-design type of architecture. > > I'm inclined to agree with you, but we should address these issues now, while > we have relatively few devices impacted by them. I fear that ignoring the > problem and hoping it will go away by itself will bring us to a difficult > position in the future. We should show the industry in which direction we > would like it to go. I'm all about showing the industry in with direction we would like it to go. We want that all Linux-supported architectures/sub-architectures support inter-core communications in kernelspace, in a more efficient way that it would happen if such communication would happen in userspace. Thanks, Mauro.