From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0961C433E0 for ; Wed, 24 Feb 2021 06:50:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9246264E60 for ; Wed, 24 Feb 2021 06:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234276AbhBXGuF convert rfc822-to-8bit (ORCPT ); Wed, 24 Feb 2021 01:50:05 -0500 Received: from relay10.mail.gandi.net ([217.70.178.230]:53899 "EHLO relay10.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234260AbhBXGtl (ORCPT ); Wed, 24 Feb 2021 01:49:41 -0500 Received: from xps13 (lfbn-tou-1-972-113.w86-210.abo.wanadoo.fr [86.210.203.113]) (Authenticated sender: miquel.raynal@bootlin.com) by relay10.mail.gandi.net (Postfix) with ESMTPSA id 3E15A240005; Wed, 24 Feb 2021 06:48:51 +0000 (UTC) Date: Wed, 24 Feb 2021 07:48:50 +0100 From: Miquel Raynal To: mdalam@codeaurora.org Cc: mani@kernel.org, boris.brezillon@collabora.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, sricharan@codeaurora.org, mdalam=codeaurora.org@codeaurora.org Subject: Re: [PATCH] mtd: rawnand: qcom: update last code word register Message-ID: <20210224074850.0c74154d@xps13> In-Reply-To: <38da9d1d4a96f1b42ba0b194da265e6b@codeaurora.org> References: <1614024267-12529-1-git-send-email-mdalam@codeaurora.org> <20210223173449.1a55df1e@xps13> <38da9d1d4a96f1b42ba0b194da265e6b@codeaurora.org> Organization: Bootlin X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, mdalam@codeaurora.org wrote on Wed, 24 Feb 2021 10:09:48 +0530: > On 2021-02-24 01:13, mdalam@codeaurora.org wrote: > > On 2021-02-23 22:04, Miquel Raynal wrote: > >> Hello, > >> >> Md Sadre Alam wrote on Tue, 23 Feb 2021 > >> 01:34:27 +0530: > >> >>> From QPIC version 2.0 onwards new register got added to read last > >> >> a new > >> >>> codeword. This change will add the READ_LOCATION_LAST_CW_n register. > >> >> Add support for this READ_LOCATION_LAST_CW_n register. > >> >>> >>> For first three code word READ_LOCATION_n register will be > >>> use.For last code word READ_LOCATION_LAST_CW_n register will be > >>> use. > >> >> " > >> In the case of QPIC v2, codewords 0, 1 and 2 will be accessed through > >> READ_LOCATION_n, while codeword 3 will be accessed through > >> READ_LOCATION_LAST_CW_n. > >> " > >> >> When I read my own sentence, I feel that there is something wrong. > >> If there are only 4 codewords, I guess a QPIC v2 is able to use > >> READ_LOCATION_3 or READ_LOCATION_LAST_CW_0 interchangeably. Isn't it? > >> >> I guess the point of having these "last_cw_n" registers is to support > >> up to 8 codewords, am I wrong? If this the case, the current patch > >> completely fails doing that I don't get the point of such change. > > > > This register is only use to read last code word. > > > > I have address all the comments from all the previous sub sequent > > patches and pushed > > all patches in only one series. > > > > Please check. > > The registers READ_LOCATION & READ_LOCATION_LAST are not associated with number of code words. > These two registers are used to access the location inside a code word. Ok. Can you please explain what is a location then? Or point me to a datasheet that explains it. Bottom line question: why having READ_LOCATION_0, _1,... an READ_LOCATION_LAST_0, _1, etc? > So whether we are having 4 code words > or 8 code words it doesn't matter. If we wanted access the location within normal code word we have to > use READ_LOCATION register and if we wanted to access location in last code word then we have to use > READ_LOCATION_LAST. > > > >> >>> Signed-off-by: Md Sadre Alam Thanks, Miquèl