Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754481AbbKBRGN (ORCPT ); Mon, 2 Nov 2015 12:06:13 -0500 Received: from mail-gw3-out.broadcom.com ([216.31.210.64]:41404 "EHLO mail-gw3-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753303AbbKBRGJ convert rfc822-to-8bit (ORCPT ); Mon, 2 Nov 2015 12:06:09 -0500 X-IronPort-AV: E=Sophos;i="5.20,234,1444719600"; d="scan'208";a="79254462" From: Anup Patel To: Brian Norris CC: David Woodhouse , Linux MTD , Rob Herring , Pawel Moll , Mark Rutland , Catalin Marinas , Will Deacon , Sudeep Holla , Ian Campbell , "Kumar Gala" , Ray Jui , Scott Branden , Florian Fainelli , "Pramod Kumar" , Vikram Prakash , Sandeep Tripathy , Linux ARM Kernel , Device Tree , Linux Kernel , bcm-kernel-feedback-list Subject: RE: [PATCH v5 2/3] mtd: brcmnand: Force 8bit mode before doing nand_scan_ident() Thread-Topic: [PATCH v5 2/3] mtd: brcmnand: Force 8bit mode before doing nand_scan_ident() Thread-Index: AQHREuCQFJhI5TOM9Umj7w+ltZHGsp6E50cAgAQTs8A= Date: Mon, 2 Nov 2015 17:06:08 +0000 Message-ID: <39063E8F96E11742B35A201CC5D095B7B063F0@SJEXCHMB10.corp.ad.broadcom.com> References: <1446188361-15146-1-git-send-email-anup.patel@broadcom.com> <1446188361-15146-3-git-send-email-anup.patel@broadcom.com> <20151030194744.GJ13239@google.com> In-Reply-To: <20151030194744.GJ13239@google.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.16.203.100] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2253 Lines: 54 > -----Original Message----- > From: Brian Norris [mailto:computersforpeace@gmail.com] > Sent: 31 October 2015 01:18 > To: Anup Patel > Cc: David Woodhouse; Linux MTD; Rob Herring; Pawel Moll; Mark Rutland; > Catalin Marinas; Will Deacon; Sudeep Holla; Ian Campbell; Kumar Gala; Ray Jui; > Scott Branden; Florian Fainelli; Pramod Kumar; Vikram Prakash; Sandeep > Tripathy; Linux ARM Kernel; Device Tree; Linux Kernel; bcm-kernel-feedback-list > Subject: Re: [PATCH v5 2/3] mtd: brcmnand: Force 8bit mode before doing > nand_scan_ident() > > On Fri, Oct 30, 2015 at 12:29:20PM +0530, Anup Patel wrote: > > Just like other NAND controllers, > > ^^ That part isn't strictly true. While READ ID data only comes out on the lower 8 > bits, that doesn't *actually* mean you can't get valid data from a 16-bit bus in > general; you just have to drop the upper 8 bits. That's what these two commits > did for read ID and parameter page read commands: > > commit 3dad2344e92c6e1aeae42df1c4824f307c51bcc7 > Author: Brian Norris > Date: Wed Jan 29 14:08:12 2014 -0800 > > mtd: nand: force NAND_CMD_READID onto 8-bit bus > > commit bd9c6e99b58255b9de1982711ac9487c9a2f18be > Author: Brian Norris > Date: Fri Nov 29 22:04:28 2013 -0800 > > mtd: nand: don't use read_buf for 8-bit ONFI transfers > > > the NAND READID command only works > > in 8bit mode for all versions of BRCMNAND controller. > > But I presume *this* statement is actually true. This NAND controller doesn't > exactly give us a fully-flexible READID / read_byte / read_word command, as it > works at a higher level than that (although LOW_LEVEL_OP gives us this > flexibility now). I could imagine (though I never tested 16-bit NAND) that 16-bit > READID is broken. > > BTW, did you ask the HW designer about this? It'd be nice to be 100% sure. Yes, we had a discussed with HW designers and they confirmed that READID command will only work in 8bit mode. Regards, Anup -- 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/