Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755930Ab3GUQeA (ORCPT ); Sun, 21 Jul 2013 12:34:00 -0400 Received: from mail-oa0-f51.google.com ([209.85.219.51]:53916 "EHLO mail-oa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755793Ab3GUQd5 (ORCPT ); Sun, 21 Jul 2013 12:33:57 -0400 MIME-Version: 1.0 In-Reply-To: <20130718182504.GA7497@arwen.pp.htv.fi> References: <1374165830-6367-1-git-send-email-r.sricharan@ti.com> <1374165830-6367-2-git-send-email-r.sricharan@ti.com> <20130718182504.GA7497@arwen.pp.htv.fi> Date: Sun, 21 Jul 2013 18:33:57 +0200 Message-ID: Subject: Re: [PATCH 1/3] misc: Add crossbar driver From: Linus Walleij To: Felipe Balbi Cc: Sricharan R , "linux-kernel@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "linux-doc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux-OMAP , ext Tony Lindgren , Russell King - ARM Linux , Nishanth Menon , Rajendra Nayak Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1649 Lines: 37 On Thu, Jul 18, 2013 at 8:25 PM, Felipe Balbi wrote: >> The Peripheral irq/dma requests are connected to one crossbar's input >> and the output of the crossbar is connected to controller's input >> line. On POR, there are some mappings which are done by default. >> Those peripherals which do not have a mapping on POR, should be configured >> to route its requests using the crossbar. (...) > why isn't this done under pinctrl ? If all it does is mux DMA and IRQ > request lines, it should be written as a pinctrl driver no ? Actually I was thinking about this at one time when designing pinctrl, "what if we face the problem of arbitrary signal multiplexing?" However pin control is named for what it does and also controls things like the electrical properties of pins, biasing and so on which is ill applicable here. I would rather say that the pin multiplexing portions of pin control could be rewritten to use a more generic component dealing with arbitrary line multiplexing, i.e. something under /lib and maybe then move over some generic concepts such as the function to group mapping. The same concept as found here is found in the muxes used by drivers/dma/amba-pl08x.c back-ends on ARM reference hardware which is also multiplexing DMA signals. In that case we have done platform-specific hooks and implemented this in the per-machine platform code. 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/