Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753224Ab3E2FOu (ORCPT ); Wed, 29 May 2013 01:14:50 -0400 Received: from mail-pb0-f43.google.com ([209.85.160.43]:33537 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751953Ab3E2FOt convert rfc822-to-8bit (ORCPT ); Wed, 29 May 2013 01:14:49 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: [RFC PATCHv4 1/6] arm: TI-Nspire platform code From: Daniel Tang In-Reply-To: <201305271715.02385.arnd@arndb.de> Date: Wed, 29 May 2013 15:14:41 +1000 Cc: "linux-arm-kernel@lists.infradead.org" , "linux@arm.linux.org.uk ARM Linux" , Linus Walleij , "fabian@ritter-vogt.de Vogt" , Lionel Debroux , "linux-kernel@vger.kernel.org" Content-Transfer-Encoding: 8BIT Message-Id: <10704A21-6BEC-42DC-BB1E-88A0E87D288B@gmail.com> References: <1369480087-24786-1-git-send-email-dt.tangr@gmail.com> <201305270856.19456.arnd@arndb.de> <201305271715.02385.arnd@arndb.de> To: Arnd Bergmann X-Mailer: Apple Mail (2.1503) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1785 Lines: 44 On 28/05/2013, at 1:15 AM, Arnd Bergmann wrote: > On Monday 27 May 2013, Daniel Tang wrote: >> Before any peripheral is accessed. I.e. before the clocksource and irqchip >> drivers. > > The irqchip comes first, and by that time, you can actually call > of_iomap(). > >> The write to the port is supposed to ensure all mmio peripherals can be >> accessed. Without it, access to certain peripherals will result in >> undefined reads or ignored writes. >> >> On second thoughts, would this actually be the job of the boot loader? > > Doing it in the boot loader would certainly simplify things. I wonder > about the dynamic aspects of power management though: It might be > better to expose the individual bits of this register through a proper > driver. The boot loader can start out enabling everything, but then > you turn off everything that is not needed when that driver gets > loaded. That's the idea for the long term. For now though, I'll probably just let the bootloader enable everything and work on a proper driver for power management later. > > I'm still not sure what the register actually does: Does it > control reset lines, clock signals, voltage regulators or something > else? These things all have their own subsystems, and then there > is also the power domain framework. To be perfectly honest, I'm not too sure. The documentation for the TI-Nspire is all gathered from reverse engineering and all it says is that register "disables bus access to peripherals". > > Arnd Cheers, Daniel Tang-- 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/