From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-gw2-out.broadcom.com ([216.31.210.63]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YqQr1-0003fV-Mt for linux-mtd@lists.infradead.org; Thu, 07 May 2015 18:49:04 +0000 Message-ID: <554BB386.4070704@broadcom.com> Date: Thu, 7 May 2015 11:48:38 -0700 From: Ray Jui MIME-Version: 1.0 To: Brian Norris , Arnd Bergmann Subject: Re: [PATCH v3 06/10] mtd: brcmstb_nand: add SoC-specific support References: <1430935194-7579-1-git-send-email-computersforpeace@gmail.com> <7101952.uOJDgn7tgf@wuerfel> <20150506204910.GJ32500@ld-irv-0074> <20781942.cIPodTiNzG@wuerfel> <20150507184246.GO32500@ld-irv-0074> In-Reply-To: <20150507184246.GO32500@ld-irv-0074> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: devicetree@vger.kernel.org, Florian Fainelli , Scott Branden , Corneliu Doban , Kevin Cernekee , =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , linux-kernel@vger.kernel.org, Dan Ehrenberg , Jonathan Richardson , Anatol Pomazao , Gregory Fong , bcm-kernel-feedback-list@broadcom.com, linux-mtd@lists.infradead.org, Dmitry Torokhov List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 5/7/2015 11:42 AM, Brian Norris wrote: > 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. > Yes, we must configure the bus before the after each data/cache registers access, because it changes the APB bus endianess. Thanks, Ray