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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0363FC77B6C for ; Thu, 13 Apr 2023 08:23:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229928AbjDMIXH (ORCPT ); Thu, 13 Apr 2023 04:23:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229548AbjDMIXE (ORCPT ); Thu, 13 Apr 2023 04:23:04 -0400 Received: from relay10.mail.gandi.net (relay10.mail.gandi.net [IPv6:2001:4b98:dc4:8::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 247F7E2 for ; Thu, 13 Apr 2023 01:22:57 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 6464424000A; Thu, 13 Apr 2023 08:22:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1681374176; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ciag85mAmF6PS4e2a/+yCh2UQDbtdxy+oAzmgl6ZOwY=; b=XVLz1VEi8sbuAHXlIGv24JjCyZBV7wOiY3rPkDej9VhCaJyjmppyFWq9FrQ4uvDiNAbTsh BomeLjiGd2coZifqVaoEk75tlc7HjTN/sXsMSRdicSglQA3L9ozgoDRH2w7GpvGElJf/wD yWZeD6/mteB3R3fG4M8PfioM2PASX86g7aAiutruu4+v7zH43e/7K3AKzmJMJvUuvjkpiN +RqkKT7PFpqBCs1zrqEt422Pj8hdyNBFSpN3WGRi8vM7kIs8QkhpMS49jK0yOUln7gOodd 8/aJ7aKZvdtqgnmMgtTLGsWVogZgkpUikiUEzlTkzAy3PU2u8/RRUH2nVmoykw== Date: Thu, 13 Apr 2023 10:22:53 +0200 From: Miquel Raynal To: Liang Yang Cc: Arseniy Krasnov , Richard Weinberger , Vignesh Raghavendra , Neil Armstrong , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Jianxin Pan , Yixun Lan , oxffffaa@gmail.com, kernel@sberdevices.ru, linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org, "yonghui.yu" Subject: Re: [PATCH v1 4/5] mtd: rawnand: meson: clear OOB buffer before read Message-ID: <20230413102253.2ee6bae4@xps-13> In-Reply-To: <0c61eaae-053e-5768-a533-70b2ff0cc95d@amlogic.com> References: <20230412061700.1492474-1-AVKrasnov@sberdevices.ru> <20230412061700.1492474-5-AVKrasnov@sberdevices.ru> <20230412094400.3c82f631@xps-13> <20230412113654.183350d0@xps-13> <4eace0a0-f6af-7d99-a52f-7913a2139330@sberdevices.ru> <20230412141824.755b2bca@xps-13> <20230412145715.58c2be4a@xps-13> <7c996832-258f-001c-56bd-87bbdf23eeaa@amlogic.com> <20230412163214.0c764bb3@xps-13> <0c61eaae-053e-5768-a533-70b2ff0cc95d@amlogic.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Liang, liang.yang@amlogic.com wrote on Thu, 13 Apr 2023 13:32:03 +0800: > Hi Miquel, >=20 > On 2023/4/12 22:32, Miquel Raynal wrote: > > [ EXTERNAL EMAIL ] > >=20 > > Hello, > >=20 > > liang.yang@amlogic.com wrote on Wed, 12 Apr 2023 22:04:28 +0800: > > =20 > >> Hi Miquel and Arseniy, > >> > >> On 2023/4/12 20:57, Miquel Raynal wrote: =20 > >>> [ EXTERNAL EMAIL ] > >>> > >>> Hi Arseniy, > >>> > >>> avkrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 15:22:26 +0300: =20 > >>> >>>> On 12.04.2023 15:18, Miquel Raynal wrote: =20 > >>>>> Hi Arseniy, > >>>>> > >>>>> avkrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 13:14:52 +0300: = =20 > >>>>> >>>> On 12.04.2023 12:36, Miquel Raynal wrote: =20 > >>>>>>> Hi Arseniy, > >>>>>>> > >>>>>>> avkrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 12:20:55 +0300= : =20 > >>>>>>> >>>>>> On 12.04.2023 10:44, Miquel Raynal wrote: =20 > >>>>>>>>> Hi Arseniy, > >>>>>>>>> > >>>>>>>>> AVKrasnov@sberdevices.ru wrote on Wed, 12 Apr 2023 09:16:58 +03= 00: =20 > >>>>>>>>> >>>>>>>> This NAND reads only few user's bytes in ECC m= ode (not full OOB), so =20 > >>>>>>>>> > >>>>>>>>> "This NAND reads" does not look right, do you mean "Subpage rea= ds do > >>>>>>>>> not retrieve all the OOB bytes,"? =20 > >>>>>>>>> >>>>>>>> fill OOB buffer with zeroes to not return garb= age from previous reads =20 > >>>>>>>>>> to user. > >>>>>>>>>> Otherwise 'nanddump' utility prints something like this for ju= st erased > >>>>>>>>>> page: > >>>>>>>>>> > >>>>>>>>>> ... > >>>>>>>>>> 0x000007f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > >>>>>>>>>> OOB Data: ff ff ff ff 00 00 ff ff 80 cf 22 99 cb ad d3 be > >>>>>>>>>> OOB Data: 63 27 ae 06 16 0a 2f eb bb dd 46 74 41 8e 88 6e > >>>>>>>>>> OOB Data: 38 a1 2d e6 77 d4 05 06 f2 a5 7e 25 eb 34 7c ff > >>>>>>>>>> OOB Data: 38 ea de 14 10 de 9b 40 33 16 6a cc 9d aa 2f 5e > >>>>>>>>>> > >>>>>>>>>> Signed-off-by: Arseniy Krasnov > >>>>>>>>>> --- > >>>>>>>>>> drivers/mtd/nand/raw/meson_nand.c | 5 +++++ > >>>>>>>>>> 1 file changed, 5 insertions(+) > >>>>>>>>>> > >>>>>>>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/n= and/raw/meson_nand.c > >>>>>>>>>> index f84a10238e4d..f2f2472cb511 100644 > >>>>>>>>>> --- a/drivers/mtd/nand/raw/meson_nand.c > >>>>>>>>>> +++ b/drivers/mtd/nand/raw/meson_nand.c > >>>>>>>>>> @@ -858,9 +858,12 @@ static int meson_nfc_read_page_sub(struct= nand_chip *nand, > >>>>>>>>>> static int meson_nfc_read_page_raw(struct nand_chip *nand, = u8 *buf, > >>>>>>>>>> int oob_required, int page) > >>>>>>>>>> { > >>>>>>>>>> + struct mtd_info *mtd =3D nand_to_mtd(nand); > >>>>>>>>>> u8 *oob_buf =3D nand->oob_poi; > >>>>>>>>>> int ret; =20 > >>>>>>>>>> >>>>>>>> + memset(oob_buf, 0, mtd->oobsize); =20 > >>>>>>>>> > >>>>>>>>> I'm surprised raw reads do not read the entire OOB? =20 > >>>>>>>> > >>>>>>>> Yes! Seems in case of raw access (what i see in this driver) num= ber of OOB bytes read > >>>>>>>> still depends on ECC parameters: for each portion of data covere= d with ECC code we can > >>>>>>>> read it's ECC code and "user bytes" from OOB - it is what i see = by dumping DMA buffer by > >>>>>>>> printk(). For example I'm working with 2K NAND pages, each page = has 2 x 1K ECC blocks. > >>>>>>>> For each ECC block I have 16 OOB bytes which I can access by rea= d/write. Each 16 bytes > >>>>>>>> contains 2 bytes of user's data and 14 bytes ECC codes. So when = I read page in raw mode > >>>>>>>> controller returns 32 bytes (2 x (2 + 14)) of OOB. While OOB is = reported as 64 bytes. =20 > >>>>>>> > >>>>>>> In all modes, when you read OOB, you should get the full OOB. The= fact > >>>>>>> that ECC correction is enabled or disabled does not matter. If th= e NAND > >>>>>>> features OOB sections of 64 bytes, you should get the 64 bytes. > >>>>>>> > >>>>>>> What happens sometimes, is that some of the bytes are not protect= ed > >>>>>>> against bitflips, but the policy is to return the full buffer. =20 > >>>>>> > >>>>>> Ok, so to clarify case for this NAND controller: > >>>>>> 1) In both ECC and raw modes i need to return the same raw OOB dat= a (e.g. user bytes > >>>>>> + ECC codes)? =20 > >>>>> > >>>>> Well, you need to cover the same amount of data, yes. But in the ECC > >>>>> case the data won't be raw (at least not all of it). =20 > >>>> > >>>> So "same amount of data", in ECC mode current implementation returns= only user OOB bytes (e.g. > >>>> OOB data excluding ECC codes), in raw it returns user bytes + ECC co= des. IIUC correct > >>>> behaviour is to always return user bytes + ECC codes as OOB data eve= n in ECC mode ? =20 > >>> > >>> If the page are 2k+64B you should read 2k+64B when OOB are requested. > >>> > >>> If the controller only returns 2k+32B, then perform a random read to > >>> just move the read pointer to mtd->size + mtd->oobsize - 32 and > >>> retrieve the missing 32 bytes? =20 > >> > >> 1) raw read can read out the whole page data 2k+64B, decided by the le= n in the controller raw read command: > >> cmd =3D (len & GENMASK(5, 0)) | scrambler | DMA_DIR(dir); > >> after that, the missing oob bytes(not used) can be copied from meson_c= hip->data_buf. so the implementation of meson_nfc_read_page_raw() is like t= his if need. > >> { > >> ...... > >> meson_nfc_read_page_sub(nand, page, 1); > >> meson_nfc_get_data_oob(nand, buf, oob_buf); > >> oob_len =3D (nand->ecc.bytes + 2) * nand->ecc.steps; > >> memcpy(oob_buf + oob_len, meson_chip->data_buf + oob_len, mtd->oobsi= ze - oob_len); > >> > >> } > >> 2) In ECC mode, the controller can't bring back the missing OOB bytes.= it can read out the user bytes and ecc bytes per meson_ooblayout_ops defin= e. =20 > >=20 > > And then (if oob_required) you can bring the missing bytes with > > something along: > > nand_change_read_column_op(chip, mtd->writesize + oob_len, > > oob_buf + oob_len, > > mtd->oobsize - oob_len, > > false); > > Should not be a huge performance hit. =20 >=20 > After finishing ECC mode reading, the column address internal in NAND dev= ice should be the right pos; it doesn't need to change the column again. so= adding controller raw read for the missing bytes after ECC reading may wor= ks. Yes, if the last byte read is the one right before the "missing" bytes, then that will work. Thanks, Miqu=C3=A8l