Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753576AbaGKMip (ORCPT ); Fri, 11 Jul 2014 08:38:45 -0400 Received: from mail-oa0-f42.google.com ([209.85.219.42]:45749 "EHLO mail-oa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753289AbaGKMim (ORCPT ); Fri, 11 Jul 2014 08:38:42 -0400 MIME-Version: 1.0 In-Reply-To: <20140711122744.GE3003@tarshish> References: <1403091577-10232-1-git-send-email-harinik@xilinx.com> <5cc8b89b-20ff-4fa9-92dd-bb2f6d3512d8@BY2FFO11FD030.protection.gbl> <20140707152309.GH4939@tarshish> <20140711062811.GC3003@tarshish> <20140711122744.GE3003@tarshish> Date: Fri, 11 Jul 2014 14:38:41 +0200 Message-ID: Subject: Re: [PATCH v2 1/2] gpio: Add driver for Zynq GPIO controller From: Linus Walleij To: Baruch Siach Cc: =?UTF-8?Q?S=C3=B6ren_Brinkmann?= , Mark Rutland , Alexandre Courbot , Harini Katakam , Pawel Moll , "ijc+devicetree@hellion.org.uk" , "linux-doc@vger.kernel.org" , Michal Simek , Harini Katakam , "linux-kernel@vger.kernel.org" , "linux-gpio@vger.kernel.org" , "devicetree@vger.kernel.org" , Rob Herring , Rob Landley , Kumar Gala , Grant Likely , Harini Katakam , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 11, 2014 at 2:27 PM, Baruch Siach wrote: > On Fri, Jul 11, 2014 at 02:06:29PM +0200, Linus Walleij wrote: >> So given that an FPGA is a piece of hardware, it should have its firmware >> loaded from the kernel and a kernel driver communicating with it I guess? >> >> I feel the smell of a huge bundle of userspace drivers for something that >> should be handled by the kernel. > > The FPGA can be loaded using simple SPI bit-banging, for which I used the > userspace SPI interface. Nothing fancy, just a few hundred LoC. Kernel driver > along with a userspace interface to be maintained forever for this task seems > an overkill to me. OK I'd say yes maybe it's like a modem on the other side of a serial line then, and then it makes sense to have that as a userspace thing. It's just that when it comes to anything relating to the electrical connections on the board, that stuff should be in some device tree or similar HW description format, and then this needs to be parsed by userspace too, and ... yuck. It's just so incoherent in a helicopter view. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/