Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751799AbaA3IiV (ORCPT ); Thu, 30 Jan 2014 03:38:21 -0500 Received: from mail-wg0-f51.google.com ([74.125.82.51]:43030 "EHLO mail-wg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750996AbaA3IiT (ORCPT ); Thu, 30 Jan 2014 03:38:19 -0500 Message-ID: <52EA0F76.6000300@gmail.com> Date: Thu, 30 Jan 2014 09:38:14 +0100 From: boris brezillon dev User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: =?UTF-8?B?SGVucmlrIE5vcmRzdHLDtm0=?= , linux-sunxi@googlegroups.com CC: Maxime Ripard , Rob Landley , Russell King , David Woodhouse , Grant Likely , Brian Norris , Jason Gunthorpe , Arnd Bergmann , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , linux-mtd@lists.infradead.org, dev@linux-sunxi.org, Rob Herring Subject: Re: [linux-sunxi] Re: [RFC PATCH v2 09/14] mtd: nand: add sunxi NFC dt bindings doc References: <1391006064-28890-1-git-send-email-b.brezillon.dev@gmail.com> <1391006064-28890-10-git-send-email-b.brezillon.dev@gmail.com> <1391035079.14902.3.camel@localhost> In-Reply-To: <1391035079.14902.3.camel@localhost> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Henrik, On 29/01/2014 23:37, Henrik Nordström wrote: > ons 2014-01-29 klockan 11:11 -0600 skrev Rob Herring: > >> Isn't allwinner,rb implied by a lack of rb-gpios property. Or no R/B >> pin is an option? If so, don't you need some fixed time delay >> properties like max erase time? >> >> rb-gpios could be added to the generic nand binding as well. > The Allwinner NAND controller have dedicated RB pins when NAND is > enabled, only MUXed with other functions when NAND is not enabled. > > Leaving RB unconnected is not a valid hardware configuration. The > controller internal timing engine depends on being able to sense RB to > sequence NAND commands properly. This is not true (at least in this driver). It was in yuq's driver because he was using the NFC_WAIT_FLAG ,and in this case the controller wait for the native R/B pin to be high before considering the CMD is complete. This driver choose the appropriate way to test the R/B state of the NAND chip according to what was specified in the DT: - allwinner,rb: native R/B id. These pins will be used by the NAND controller to test the R/B state. Only 0 and 1 are valid because the NAND controller only support 2 R/B pins. - rb-gpios: gpio used for R/B tests. This is a simple GPIO and will use the GPIO subsystem to test the R/B pin state. - none: the NAND base code will wait some time before and send STATUS cmd to the NAND to check its status. BTW, the controller supports 8 CS (8 NAND chips), but only have 2 native R/B pins, this means you'll have to use the GPIO or standard GET_STATUS method if you connect 3 or more NAND chips. And for the record, I still think the rb-gpios property (or whatever common name you choose: nand-rb-gpios ?) should be part of the generic NAND binding, because other controllers (at least the atmel one :)) use GPIOs to test R/B state. Best Regards, Boris > > Regards > Henrik > -- 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/