Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754302AbaKXOcR (ORCPT ); Mon, 24 Nov 2014 09:32:17 -0500 Received: from arrakis.dune.hu ([78.24.191.176]:39239 "EHLO arrakis.dune.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753414AbaKXOcO (ORCPT ); Mon, 24 Nov 2014 09:32:14 -0500 MIME-Version: 1.0 In-Reply-To: <1416796846-28149-7-git-send-email-cernekee@gmail.com> References: <1416796846-28149-1-git-send-email-cernekee@gmail.com> <1416796846-28149-7-git-send-email-cernekee@gmail.com> From: Jonas Gorski Date: Mon, 24 Nov 2014 15:31:27 +0100 Message-ID: Subject: Re: [PATCH V3 06/11] irqchip: bcm7120-l2: Change DT binding to allow non-contiguous IRQEN/IRQSTAT To: Kevin Cernekee Cc: Ralf Baechle , Florian Fainelli , Jon Fraser , Dmitry Torokhov , Thomas Gleixner , Jason Cooper , Arnd Bergmann , computersforpeace@gmail.com, MIPS Mailing List , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 24, 2014 at 3:40 AM, Kevin Cernekee wrote: > To date, all supported controllers have had the IRQEN register at offset > 0x00 and the IRQSTAT register at 0x04. So in DT we would typically see > something like: > > reg = <0xf0406800 0x8>; > > We still want to support this format, but we also need to support cases > where IRQEN and IRQSTAT aren't adjacent. So, we will amend the driver to > accept an alternate format that looks like this: > > reg = <0xf0406800 0x4 0xf0406804 0x4>; > > i.e. if the first resource_size() == 4, assume that the first resource > points to IRQEN and that the next resource points to IRQSTAT. If the > first resource_size() == 8, retain the current behavior. > > Signed-off-by: Kevin Cernekee Hmm ... the more I think about this, the less I like it. Using the amount and size of the reg-properties to infer a certain layout seems rather hackish and dirty to me. Maybe we should just use different compatible match ids for that? E.g. brcm,bm7120-l2-intc for the 32-bit en/stat pairs, and e.g. brcm,bcm6368-l2-intc for the 64-bit wide one. Or maybe make the bcm63xx one a separate driver and let it share code with the bcm7120-l2-intc driver. This would avoid having to specify a lot of regs (let's assume we also add support for affinity), and cause a lot of io(re)map calls - the bcm63268 one would currently look like: reg = <0x1000002c 0x4 0x1000003c 0x4>, /* irq 0..31 -> mips irq 2 */ <0x10000028 0x4 0x10000038 0x4>, /* irq 32..63 -> mips irq 2 */ <0x10000024 0x4 0x10000034 0x4>, /* irq 64 .. 95 -> mips irq 2 */ <0x10000020 0x4 0x10000030 0x4>, /* irq 96 .. 127 -> mips irq 2 */ <0x1000004c 0x4 0x1000005c 0x4>, /* irq 0.. 31 -> mips irq 3 */ <0x10000048 0x4 0x10000058 0x4>, /* irq 32 .. 63 -> mips irq 3 */ <0x10000044 0x4 0x10000054 0x4>, /* irq 64 ... 95 -> mips irq 3 */ <0x10000040 0x4 0x10000050 0x4>; /* irq 96 ... 127 -> mips irq 3 */ where as with a different match id, we could rather allow something like reg = <0x10000020 0x20>, /* irq 0..127 -> mips irq 2 */ <0x10000040 0x20>; /* irq 0..127 -> mips irq 3 */ This would make the dts(i) files quite a bit more readable IMHO, and make it more likely that newer dts(i) files work with older kernels, e.g. where the mips irq3 routed registers were added - in the current style, the kernel would interpret these as additional irq banks. Not that I think this is expected/required to work, but it wouldn't hurt having at least a bit of backward compatibility for bisecting on a device that provides a newer dtb through the bootloader. Jonas -- 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/