From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753904Ab3CDF5h (ORCPT ); Mon, 4 Mar 2013 00:57:37 -0500 Received: from ch1ehsobe004.messaging.microsoft.com ([216.32.181.184]:51497 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750803Ab3CDF5g convert rfc822-to-8bit (ORCPT ); Mon, 4 Mar 2013 00:57:36 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: 2 X-BigFish: VS2(z3121kz98dI9371Ic89bh936eI1432Izz1f42h1ee6h1de0h1202h1e76h1d1ah1d2ah1082kzz8275bhz2dh2a8h668h839h93fhd25he5bhf0ah1288h12a5h12a9h12bdh1354h137ah13b6h1441h1504h1537h153bh162dh1631h1758h1765h18e1h190ch1946h19c3h1ad9h1155h) Message-ID: <513437DF.2030505@freescale.com> Date: Mon, 4 Mar 2013 13:57:51 +0800 From: Huang Shijie User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.24) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16 MIME-Version: 1.0 To: CC: Huang Shijie , , , , Subject: Re: [PATCH V3 1/3] mtd: add new fields to nand_flash_dev{} References: <1359349039-11510-1-git-send-email-b32955@freescale.com> <1359349039-11510-2-git-send-email-b32955@freescale.com> <1360684037.12703.117.camel@sauron.fi.intel.com> <1362234094.2745.9.camel@sauron> In-Reply-To: <1362234094.2745.9.camel@sauron> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8BIT X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2013年03月02日 22:21, Artem Bityutskiy 写道: > On Sat, 2013-02-16 at 11:56 +0800, Huang Shijie wrote: >> On Tue, Feb 12, 2013 at 11:47 PM, Artem Bityutskiy wrote: >>> On Mon, 2013-01-28 at 12:57 +0800, Huang Shijie wrote: >>>> + {"SmartMedia 256MiB 3,3V", {0, 0x71}, 512, 256, 0x4000 }, >>>> + {"SmartMedia 256MiB 3,3V ROM", {0, 0x5b}, 512, 256, 0x4000, >>>> NAND_ROM}, >>> Sorry for a possibly stupid question, but what does it buy you adding >>> another "0" to all the entries? I see you add another table, which you >>> look up if the "traditional" table does not work. Why you need to add >>> these zeroes? >> The zeros are for the maf_id. >> >> The dev_id is the second byte of the 8-byte id data. > It does not really make me understand why we add these zeroes, they > still look useless to me... Would you please be a little more verbose > about your solution? > the 8bytes id data read out by the READ ID command is in the following order: byte 0(Maker id): such as 0x98 stands for Toshiba, 0xec stands for Samsung. byte 1(device id): byte 2(used to store the chip number,cell type information): byte 3(used to store the page size, block size information) byte 4(used to store the Plane information). ........................ The current code uses the @id to store the device id(byte 1). But if we use the 8 bytes id data as the keyword, and expand the @id field to 8byte array, the device id is the second byte now. All the added zeros are for the Maker id. For example, {"SmartMedia 256MiB 3,3V", {0, 0x71}, 512, 256, 0x4000 }, We really do not use the zeros. All the zeros are added for avoiding the misunderstanding. If we do not add the zero, it will looks like: {"SmartMedia 256MiB 3,3V", {0x71}, 512, 256, 0x4000 }, The device id (0x71) becomes the first byte of 8byte id array, people will treat the 0x71 as the Maker code. thanks Huang Shijie