From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752830AbaEAX2a (ORCPT ); Thu, 1 May 2014 19:28:30 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:60081 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752752AbaEAX20 (ORCPT ); Thu, 1 May 2014 19:28:26 -0400 MIME-Version: 1.0 In-Reply-To: <20140501223629.GJ3000@lukather> References: <1398705774-12361-1-git-send-email-maxime.ripard@free-electrons.com> <20140429183758.GH15125@sirena.org.uk> <20140430180609.GC3000@lukather> <20140501011811.GF3245@sirena.org.uk> <20140501223629.GJ3000@lukather> Date: Fri, 2 May 2014 01:28:26 +0200 X-Google-Sender-Auth: IdatgL55bOAmA2IEQQV6xsfBrKQ Message-ID: Subject: Re: [PATCH] spi: Force the registration of the spidev devices From: Geert Uytterhoeven To: Maxime Ripard Cc: Mark Brown , linux-spi , "linux-kernel@vger.kernel.org" , Alexandre Belloni Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Maxime, On Fri, May 2, 2014 at 12:36 AM, Maxime Ripard wrote: > But it actually doesn't work in a case where you can't really predict > what is on the other side of the bus. Either because, on the board > you're using the pins are exposed and it's pretty much up to the user > to know what to put on it. That could be handled by DT overlays > though. > > What never works is where the device on the other side is so generic > that you really can't tell what it does. Think of a microcontroller > that would behave as a SPI slave. It's behaviour and what it does is > pretty much dependant of what we flashed on it, and suddenly the > compatible string is not the proper reprensentation anymore. So you will (hopefully soon) use overlay DT to change the DTS to match what's connected? And then you want spidev to bind to it. Would it help if DT offered a feature to add a compatible entry to a driver at runtime, cfr. /sys/bus/pci/drivers/.../new_id on PCI? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds