From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Mack Subject: Re: [PATCH v3 4/4] ARM: OMAP: gpmc: add DT bindings for GPMC timings and NAND Date: Wed, 21 Nov 2012 11:15:23 +0100 Message-ID: <50ACA9BB.7090106@gmail.com> References: <1351869956-2787-1-git-send-email-zonque@gmail.com> <1351869956-2787-5-git-send-email-zonque@gmail.com> <518397C60809E147AF5323E0420B992E3E9DA81F@DBDE01.ent.ti.com> <5097B7EE.3000508@gmail.com> <518397C60809E147AF5323E0420B992E3E9DC1F1@DBDE01.ent.ti.com> <509A2E75.5060307@gmail.com> <518397C60809E147AF5323E0420B992E3E9DE420@DBDE01.ent.ti.com> <509EA360.2050504@gmail.com> <87mwycjmdn.fsf@dell.be.48ers.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:59842 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751051Ab2KUKRh (ORCPT ); Wed, 21 Nov 2012 05:17:37 -0500 Received: by mail-bk0-f46.google.com with SMTP id q16so2815848bkw.19 for ; Wed, 21 Nov 2012 02:17:36 -0800 (PST) In-Reply-To: <87mwycjmdn.fsf@dell.be.48ers.dk> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Peter Korsgaard Cc: "Philip, Avinash" , "linux-arm-kernel@lists.infradead.org" , "paul@pwsan.com" , "Mohammed, Afzal" , "devicetree-discuss@lists.ozlabs.org" , "Nori, Sekhar" , "tony@atomide.com" , "Hunter, Jon" , "linux-omap@vger.kernel.org" On 20.11.2012 16:59, Peter Korsgaard wrote: >>>>>> "Daniel" == Daniel Mack writes: > > Hi, > > >>>> In omap2 driver NAND_ECC_HW ecc mode supports 3 ecc layout > >>>> OMAP_ECC_HAMMING_CODE_HW_ROMCODE > >>>> OMAP_ECC_BCH4_CODE_HW > >>>> OMAP_ECC_BCH8_CODE_HW > >>>> > >>>> So selection of ecc layout data should come from DT not ecc mode. > >>> > >>> Ok, I see. I would still like to set them by string rather than magic > >>> numbers that map to enum entries. Valid values would be "none", "hw", > >>> "hw-romcode", "bch4" and "bch8". Are you ok with that? > >> > >> Ok, that's nice. Better use ecc_opt instead of ecc_mode. > > Daniel> I did some more extensive tests that include reading the same > Daniel> nand pages from both U-Boot and the kernel with BCH8 ECC, and > Daniel> it turns out that -> is_elm_used needs to be set in the pdata > Daniel> in order to make this work. > > So what you're saying is that the choice of ELM or not is not just an > optimization, it really changes the ECC layout? Perhaps it should be > treated as a seperate layout (E.G. bch8-elm) then? That is what I experienced, yes. The kernel was unable to parse NAND pages that were written from U-Boot with bch8 hardware mode when the elm module was not active. Maybe someone from TI can explain that? Giving it a dedicated name would also solve the problem with the extra DT property. I'll wait until this is decided before I resend a new set that also fixes the issue with the errornousely forgotten Documentation file. Thanks, Daniel