From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-bw0-f49.google.com ([209.85.214.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1RPZZG-0006bj-63 for linux-mtd@lists.infradead.org; Sun, 13 Nov 2011 12:53:51 +0000 Received: by bkat2 with SMTP id t2so7093072bka.36 for ; Sun, 13 Nov 2011 04:53:47 -0800 (PST) Subject: Re: [PATCH v2 07/16] mtd/docg3: add OOB layout to mtdinfo From: Artem Bityutskiy To: Robert Jarzmik Date: Sun, 13 Nov 2011 14:53:43 +0200 In-Reply-To: <87vcqoiavr.fsf@free.fr> References: <1320912342-30147-1-git-send-email-robert.jarzmik@free.fr> <1320912342-30147-8-git-send-email-robert.jarzmik@free.fr> <4EBECB89.2020102@newsguy.com> <87vcqoiavr.fsf@free.fr> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Message-ID: <1321188825.2273.4.camel@koala> Mime-Version: 1.0 Cc: dwmw2@infradead.org, Mike Dunn , linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, 2011-11-13 at 11:18 +0100, Robert Jarzmik wrote: > I personally think this should be provided by the MTD API. A function > is_page_blank(ofs) could tell if the page was written or not. Now if the > function is NULL, the upper layer (UBIFS, ...) could decide _by itself_ to > assign a free OOB byte to that meaning. But IMHO it's not the drivers duty to > take these decisions to restrict the OOB, let it be done at an upper level. Probably it is a good idea to introduce an mtd_is_page_blank. But it should either work for all flashes or not introduced at all. I do not think upper layers should use OOB at all. And this interface should also work for NOR flash. Probably it should just fall-back to comparing the data with 0xFF if the driver cannot offer anything special. Artem. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752556Ab1KMMxu (ORCPT ); Sun, 13 Nov 2011 07:53:50 -0500 Received: from mail-bw0-f46.google.com ([209.85.214.46]:45678 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083Ab1KMMxs (ORCPT ); Sun, 13 Nov 2011 07:53:48 -0500 Subject: Re: [PATCH v2 07/16] mtd/docg3: add OOB layout to mtdinfo From: Artem Bityutskiy Reply-To: dedekind1@gmail.com To: Robert Jarzmik Cc: Mike Dunn , dwmw2@infradead.org, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Date: Sun, 13 Nov 2011 14:53:43 +0200 In-Reply-To: <87vcqoiavr.fsf@free.fr> References: <1320912342-30147-1-git-send-email-robert.jarzmik@free.fr> <1320912342-30147-8-git-send-email-robert.jarzmik@free.fr> <4EBECB89.2020102@newsguy.com> <87vcqoiavr.fsf@free.fr> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.0.2 (3.0.2-3.fc15) Content-Transfer-Encoding: 7bit Message-ID: <1321188825.2273.4.camel@koala> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2011-11-13 at 11:18 +0100, Robert Jarzmik wrote: > I personally think this should be provided by the MTD API. A function > is_page_blank(ofs) could tell if the page was written or not. Now if the > function is NULL, the upper layer (UBIFS, ...) could decide _by itself_ to > assign a free OOB byte to that meaning. But IMHO it's not the drivers duty to > take these decisions to restrict the OOB, let it be done at an upper level. Probably it is a good idea to introduce an mtd_is_page_blank. But it should either work for all flashes or not introduced at all. I do not think upper layers should use OOB at all. And this interface should also work for NOR flash. Probably it should just fall-back to comparing the data with 0xFF if the driver cannot offer anything special. Artem.