From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752885AbbBWSj3 (ORCPT ); Mon, 23 Feb 2015 13:39:29 -0500 Received: from mail-qc0-f182.google.com ([209.85.216.182]:33356 "EHLO mail-qc0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752372AbbBWSj1 (ORCPT ); Mon, 23 Feb 2015 13:39:27 -0500 Message-ID: <54EB73DC.4090507@hurleysoftware.com> Date: Mon, 23 Feb 2015 13:39:24 -0500 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Pantelis Antoniou , Tony Lindgren CC: Grant Likely , Matt Porter , Koen Kooi , Guenter Roeck , Ludovic Desroches , Rob Herring , Nicolas Ferre , devicetree@vger.kernel.org, Linux Kernel Mailing List , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone variants References: <1424271576-1952-1-git-send-email-pantelis.antoniou@konsulko.com> <1424271576-1952-4-git-send-email-pantelis.antoniou@konsulko.com> <20150219181656.GF32521@atomide.com> <9C7BFC7C-0751-4233-927F-D01AF078704B@antoniou-consulting.com> <20150219183600.GG32521@atomide.com> <145DEB3E-A20E-4390-84B1-4B30E7C3D841@antoniou-consulting.com> In-Reply-To: <145DEB3E-A20E-4390-84B1-4B30E7C3D841@antoniou-consulting.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pantelis, On 02/19/2015 01:44 PM, Pantelis Antoniou wrote: > Hi Tony, > >> On Feb 19, 2015, at 20:36 , Tony Lindgren wrote: >> >> * Pantelis Antoniou [150219 10:32]: >>>> On Feb 19, 2015, at 20:16 , Tony Lindgren wrote: >>>> >>>> Uhh I don't like the idea of duplicating the i2c-omap.c driver under >>>> arch/arm.. And in general we should initialize things later rather >>>> than earlier. >>>> >>>> What's stopping doing these quirk checks later on time with just >>>> a regular device driver, something like drivers/misc/bbone-quirks.c? >>>> >>> >>> We have no choice; we are way early in the boot process, right after >>> the device tree unflattening step. >> >> To me it seems the dt patching part should be done with minimal >> code before any driver like features.. >> > > The way it’s done right now is with minimal code. Reading the EEPROM > is required. > >>> I’ve toyed with the idea of using early platform devices but the omap-i2c driver >>> would need some tender love and care to make it work, and I didn’t want to get >>> bogged down with i2c driver details at this point. >> >> ..so how about just parse a kernel cmdline for the quirks to apply >> based on a version string or similar? That can be easily populated >> by u-boot or set manually with setenv. >> >> That leaves out the need for tinkering with i2c super early in >> the kernel for revision detection. >> > > You assume there’s going to be a bootloader… So does this patch. > diff --git a/arch/arm/mach-omap2/am33xx-dt-quirks.c b/arch/arm/mach-omap2/am33xx-dt-quirks.c [...] > + * Note that we rely on the bootloader setting up the muxes > + * (which is the case for u-boot). Regards, Peter Hurley From mboxrd@z Thu Jan 1 00:00:00 1970 From: peter@hurleysoftware.com (Peter Hurley) Date: Mon, 23 Feb 2015 13:39:24 -0500 Subject: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone variants In-Reply-To: <145DEB3E-A20E-4390-84B1-4B30E7C3D841@antoniou-consulting.com> References: <1424271576-1952-1-git-send-email-pantelis.antoniou@konsulko.com> <1424271576-1952-4-git-send-email-pantelis.antoniou@konsulko.com> <20150219181656.GF32521@atomide.com> <9C7BFC7C-0751-4233-927F-D01AF078704B@antoniou-consulting.com> <20150219183600.GG32521@atomide.com> <145DEB3E-A20E-4390-84B1-4B30E7C3D841@antoniou-consulting.com> Message-ID: <54EB73DC.4090507@hurleysoftware.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Pantelis, On 02/19/2015 01:44 PM, Pantelis Antoniou wrote: > Hi Tony, > >> On Feb 19, 2015, at 20:36 , Tony Lindgren wrote: >> >> * Pantelis Antoniou [150219 10:32]: >>>> On Feb 19, 2015, at 20:16 , Tony Lindgren wrote: >>>> >>>> Uhh I don't like the idea of duplicating the i2c-omap.c driver under >>>> arch/arm.. And in general we should initialize things later rather >>>> than earlier. >>>> >>>> What's stopping doing these quirk checks later on time with just >>>> a regular device driver, something like drivers/misc/bbone-quirks.c? >>>> >>> >>> We have no choice; we are way early in the boot process, right after >>> the device tree unflattening step. >> >> To me it seems the dt patching part should be done with minimal >> code before any driver like features.. >> > > The way it?s done right now is with minimal code. Reading the EEPROM > is required. > >>> I?ve toyed with the idea of using early platform devices but the omap-i2c driver >>> would need some tender love and care to make it work, and I didn?t want to get >>> bogged down with i2c driver details at this point. >> >> ..so how about just parse a kernel cmdline for the quirks to apply >> based on a version string or similar? That can be easily populated >> by u-boot or set manually with setenv. >> >> That leaves out the need for tinkering with i2c super early in >> the kernel for revision detection. >> > > You assume there?s going to be a bootloader? So does this patch. > diff --git a/arch/arm/mach-omap2/am33xx-dt-quirks.c b/arch/arm/mach-omap2/am33xx-dt-quirks.c [...] > + * Note that we rely on the bootloader setting up the muxes > + * (which is the case for u-boot). Regards, Peter Hurley