Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751755AbbEGSmz (ORCPT ); Thu, 7 May 2015 14:42:55 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:34570 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751358AbbEGSmw (ORCPT ); Thu, 7 May 2015 14:42:52 -0400 Date: Thu, 7 May 2015 11:42:46 -0700 From: Brian Norris To: Arnd Bergmann Cc: linux-mtd@lists.infradead.org, Dmitry Torokhov , Anatol Pomazao , Ray Jui , Corneliu Doban , Jonathan Richardson , Scott Branden , Florian Fainelli , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , bcm-kernel-feedback-list@broadcom.com, Dan Ehrenberg , Gregory Fong , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Kevin Cernekee Subject: Re: [PATCH v3 06/10] mtd: brcmstb_nand: add SoC-specific support Message-ID: <20150507184246.GO32500@ld-irv-0074> References: <1430935194-7579-1-git-send-email-computersforpeace@gmail.com> <7101952.uOJDgn7tgf@wuerfel> <20150506204910.GJ32500@ld-irv-0074> <20781942.cIPodTiNzG@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20781942.cIPodTiNzG@wuerfel> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4138 Lines: 92 On Thu, May 07, 2015 at 12:01:02PM +0200, Arnd Bergmann wrote: > On Wednesday 06 May 2015 13:49:10 Brian Norris wrote: > > On Wed, May 06, 2015 at 09:12:43PM +0200, Arnd Bergmann wrote: > > > On Wednesday 06 May 2015 10:59:50 Brian Norris wrote: > > > > + /* > > > > + * Some SoCs integrate this controller (e.g., its interrupt bits) in > > > > + * interesting ways > > > > + */ > > > > + if (of_property_read_bool(dn, "brcm,nand-soc")) { > > > > + struct device_node *soc_dn; > > > > + > > > > + soc_dn = of_parse_phandle(dn, "brcm,nand-soc", 0); > > > > + if (!soc_dn) > > > > + return -ENODEV; > > > > + > > > > + ctrl->soc = devm_brcmnand_probe_soc(dev, soc_dn); > > > > + if (!ctrl->soc) { > > > > + dev_err(dev, "could not probe SoC data\n"); > > > > + of_node_put(soc_dn); > > > > + return -ENODEV; > > > > + } > > > > + > > > > + ret = devm_request_irq(dev, ctrl->irq, brcmnand_irq, 0, > > > > + DRV_NAME, ctrl); > > > > + > > > > + /* Enable interrupt */ > > > > + ctrl->soc->ctlrdy_set_enabled(ctrl->soc, true); > > > > + > > > > + of_node_put(soc_dn); > > > > + } else { > > > > + /* Use standard interrupt infrastructure */ > > > > + ret = devm_request_irq(dev, ctrl->irq, brcmnand_ctlrdy_irq, 0, > > > > + DRV_NAME, ctrl); > > > > + } > > > > > > > > > > It looks to me like this should be handled as a nested irqchip, so the node > > > you look up gets used as the "interrupt-parent" instead, making the behavior > > > of this SoC transparent to the nand driver. > > > > You snipped the rest of the patch, which involves more than just IRQ > > handling. The same registers touch both interrupts and data bus endian > > configuration, so it can't possibly be done transparently to the NAND > > driver. > > Anything else in there? Looks like miscellaneous NAND-related control bits. AXI and APB endian configuration; several interrupt-enable bits (we only use one for now); a clock-enable; and some timing test mode bits. > The bus configuration would just involve writing > a constant value in some register, right? I'm not an expert on the Cygnus/iProc chips, but I believe the answer is no: we *must* reconfigure the bus before and after each data transaction, because it affects the rest of the core too. Others on the CC list can probably elaborate. > Doing that in the irqchip > is also a bit ugly, but may still be better overall than doing it the > way you have above. Well, the Cygnus/iProc case is more complicated as I mention. But I agree that other cases could be nicer, like bcm63138 (which only has separate interrupt status/enable registers). Do you expect a new irqchip driver for every arrangement of registers like this? There are a few similar chips that have status/enable registers in different orders, and some that combine them into a single word. Do we really need a new irqchip driver for each one? I might have done that for bcm63138 and bcm3384, except that I thought I'd have to fall back to this extra per-SoC support driver for Cygnus anyway. > > > We recently merged nested irqdomain support as well, which might help here, > > > or might not be needed. > > > > I'm not familiar with nested irqdomains. Do they address anything like > > the above problem? > > The problem that nested irqdomains address is when an interrupt is handled > by two irqchips, in particular when one irqchip handles a virtual interrupt > number that was claimed by another irqchip already. I'll do some reading on that, but it definitely doesn't address the main problem here. Brian -- 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/