Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752739AbbBWSsr (ORCPT ); Mon, 23 Feb 2015 13:48:47 -0500 Received: from li42-95.members.linode.com ([209.123.162.95]:53573 "EHLO li42-95.members.linode.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752424AbbBWSsq convert rfc822-to-8bit (ORCPT ); Mon, 23 Feb 2015 13:48:46 -0500 Subject: Re: [PATCH 3/4] arm: am33xx: DT quirks for am33xx based beaglebone variants Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2070.6\)) Content-Type: text/plain; charset=utf-8 From: Pantelis Antoniou In-Reply-To: <54EB73DC.4090507@hurleysoftware.com> Date: Mon, 23 Feb 2015 20:48:39 +0200 Cc: Tony Lindgren , 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 Content-Transfer-Encoding: 8BIT Message-Id: <8252298C-4249-49F8-91CA-8398ADEB1348@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> <54EB73DC.4090507@hurleysoftware.com> To: Peter Hurley X-Mailer: Apple Mail (2.2070.6) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2284 Lines: 69 Hi Peter, > On Feb 23, 2015, at 20:39 , Peter Hurley wrote: > > 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. > Proof of concept, first iteration… The beaglebone is just the prototype stage. >> 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 > Regards — Pantelis -- 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/