Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758189Ab3FEX0h (ORCPT ); Wed, 5 Jun 2013 19:26:37 -0400 Received: from mail-ie0-f179.google.com ([209.85.223.179]:33335 "EHLO mail-ie0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754042Ab3FEX0g convert rfc822-to-8bit (ORCPT ); Wed, 5 Jun 2013 19:26:36 -0400 MIME-Version: 1.0 In-Reply-To: References: <51AFA6DD.3000202@wwwdotorg.org> <1370469574.18839.33.camel@localhost> Date: Thu, 6 Jun 2013 00:26:35 +0100 Message-ID: Subject: Re: [Arm-netbook] getting allwinner SoC support upstream (was Re: Uploading linux (3.9.4-1)) From: "luke.leighton" To: "jonsmirl@gmail.com" Cc: Linux on small ARM machines , devicetree-discuss , Stephen Warren , Linux Kernel Mailing List , debian-arm@lists.debian.org, ARM Linux Mailing List , debian-kernel@lists.debian.org 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 Content-Length: 2670 Lines: 58 On Thu, Jun 6, 2013 at 12:07 AM, jonsmirl@gmail.com wrote: > On Wed, Jun 5, 2013 at 6:47 PM, luke.leighton wrote: >> On Wed, Jun 5, 2013 at 10:59 PM, Henrik Nordström >> wrote: >> >>>> .... and then there's the boot0 and boot1 loaders, these *do* have >> >>> no, these are not tiny. boot0 is 24KB to fit the initial embedded SRAM >>> (not cache), but boot1 is on pair with u-boot in size and runs from >>> DRAM. >> >> btw, please listen to henrik: he knows what he's talking about, as >> you can see :) henrik, thank you for correcting my technical >> misunderstandings, i'll try to remember them and not propagate >> incorrect stuff. > > This is not about the fex syntax or uboot. The root problem is needing > two sets of binding for every device driver in the kernel. Pick a > random driver like gpio-pca953x.c and look at the source. In that file > there are #ifdef CONFIG_OF_ sections. Those sections are directly > reading the FDT binary via calls like of_get_property(node, > "linux,gpio-base", &size);. If fex is added to the kernel every driver > driver will now need both a #ifdef CONFIG_OF_ section and also a > #ifdef CONFIG_FEX_ section. Doing that is just crazy. yes. which is why they haven't done it. > Is Allwinner > going to add fex support to every single device driver in the kernel? no john - they've only added it to the multiplexed sections of the drivers which they themselves have written. such as drivers/usb/sun{N}i_usb/*.[ch], drivers/block/nand/sun{N}_i, arch/arm/mach-sun{N}i and so on. even the touchscreen driver that they wrote, that's got nothing to do with any other code in the touchscreen linux kernel source tree: it's more of a "meta-"driver which even has the name of the linux kernel module that needs to be loaded and what I2C address, GPIO options etc. to pass in [normally done as modprobe options in userspace]. to be honest, there are better people to fully answer this question (alejandro and henrik are two that spring to mind) but you're definitely off-base, jon. the script.fex system deals with the pinmux issue in a very neat way that: a) has very little impact on the rest of the kernel tree [citation needed! i'm saying that: could someone please confirm if it's true] b) the linux kernel developers could, instead of criticising it, actually learn a great deal from. l. -- 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/