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=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable 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 1D50DC47247 for ; Thu, 7 May 2020 14:09:53 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E680120857 for ; Thu, 7 May 2020 14:09:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="TtDDy8X4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E680120857 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vPQUz/eprgkNS2QrvwFtOCiBlXLWXk0RNaPvJmKcq6w=; b=TtDDy8X4LNyTBz Jrs+/h2cEymKJp4pTvDZST+tKAuzMfCZJyopbmkEnQrmmZzHgjIgIeX0LwN1TrQ34R6ghG8XBd/E+ j6FvSv7lOVZfxE9Kwnw0K7YCuqk/5R6wCawltrqYkmbSLyPnET03xT453FvYMKg+3GFh/vXpTXbll BOJ/6m5wZVWcbsQBurszYkrGX4Ck0zZ6e/DaIdZAx5XDMka2TG6MkRbdcHZka9Ij9ZYfUjFdbQ9k2 hVxyZQGqRmWZJINpInFS0hO6ecE8mroICsTbSNXFPe3hzyF4eJOFcntvEEXsP5FJXXUp510VHpCpK pZz8lcyPny5tTKQ1wAsQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWhDY-0003a6-N9; Thu, 07 May 2020 14:09:40 +0000 Received: from relay1-d.mail.gandi.net ([217.70.183.193]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWhDV-0003Z9-O8 for linux-mtd@lists.infradead.org; Thu, 07 May 2020 14:09:39 +0000 X-Originating-IP: 91.224.148.103 Received: from xps13 (unknown [91.224.148.103]) (Authenticated sender: miquel.raynal@bootlin.com) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 49CA0240011; Thu, 7 May 2020 14:09:32 +0000 (UTC) Date: Thu, 7 May 2020 16:09:30 +0200 From: Miquel Raynal To: Boris Brezillon Subject: Re: [PATCH v3 2/8] lib/bch: Allow easy bit swapping Message-ID: <20200507160930.58f6afe7@xps13> In-Reply-To: <20200507134330.6e8a9f80@collabora.com> References: <20200507110034.14736-1-miquel.raynal@bootlin.com> <20200507110034.14736-3-miquel.raynal@bootlin.com> <20200507134330.6e8a9f80@collabora.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200507_070938_060647_9348F7F6 X-CRM114-Status: GOOD ( 31.63 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, Michal Simek , Vignesh Raghavendra , Tudor Ambarus , Richard Weinberger , Rob Herring , linux-mtd@lists.infradead.org, Thomas Petazzoni , Naga Sureshkumar Relli , Ivan Djelic Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Boris Brezillon wrote on Thu, 7 May 2020 13:43:30 +0200: > On Thu, 7 May 2020 13:00:28 +0200 > Miquel Raynal wrote: > > > From: Boris Brezillon > > Hehe. I sent a raw diff and now there's my name on this patch :-). > Given you debugged/polished it, I'd rather have you take the ownership > here. > > > > > It seems that several hardware ECC engine use a swapped representation > > of bytes compared to software. > > Some more details here. I think it has to do with how the ECC engine > is wired to the NAND controller or the order the bits are passed to the > HW BCH logic. Given the sunxi NAND controller driver has the same > bit-swapping, I suspect it's actually pretty common. I'll add these details. > > > It means that when the software BCH > > engine is working in conjunction with data generated with hardware, we > > must swap the bits inside bytes, eg: > > > > 0x0A = b0000_1010 -> b0101_0000 = 0x50 > > > > Make it possible just by flipping a boolean in the BCH control > > ^ by adding a swap_bits boolen to the ... Yeah I see. > > > structure. > > Regarding the implementation itself, I came up with something simple > because I didn't want to spend too much time looking at how things > could be changed to avoid those swap_bits(). I suspect we can prepare > the ->a_{mod,pow}_tab tables to avoid that. Ivan, any opinion? > > Note that we can also optimize that in a second step, so Miquel can get > the rest of the series merged. > > > > > Signed-off-by: Boris Brezillon > > Signed-off-by: Miquel Raynal > > Cc: Ivan Djelic > > --- > > include/linux/bch.h | 1 + > > lib/bch.c | 84 ++++++++++++++++++++++++++++++++++++++------- > > 2 files changed, 72 insertions(+), 13 deletions(-) > > > > diff --git a/include/linux/bch.h b/include/linux/bch.h > > index 9c35e7cd5890..c42f50cacfdc 100644 > > --- a/include/linux/bch.h > > +++ b/include/linux/bch.h > > @@ -51,6 +51,7 @@ struct bch_control { > > int *cache; > > struct gf_poly *elp; > > struct gf_poly *poly_2t[4]; > > + bool swap_bits; > > This new field should be documented. Indeed. > > > }; > > > > struct bch_control *bch_init(int m, int t, unsigned int prim_poly); > > diff --git a/lib/bch.c b/lib/bch.c > > index 1091841ac716..81bf8b426eea 100644 > > --- a/lib/bch.c > > +++ b/lib/bch.c > > @@ -114,6 +114,49 @@ struct gf_poly_deg1 { > > unsigned int c[2]; > > }; > > > > +static u8 swap_bits_table[] = { > > + 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, > > + 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, > > + 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, > > + 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, > > + 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, > > + 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, > > + 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, > > + 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, > > + 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, > > + 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, > > + 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, > > + 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, > > + 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, > > + 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, > > + 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, > > + 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, > > + 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, > > + 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, > > + 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, > > + 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, > > + 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, > > + 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, > > + 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, > > + 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, > > + 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, > > + 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, > > + 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, > > + 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, > > + 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, > > + 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, > > + 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, > > + 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff, > > +}; > > + > > +static u8 swap_bits(struct bch_control *bch, u8 in) > > +{ > > + if (!bch->swap_bits) > > + return in; > > + > > + return swap_bits_table[in]; > > +} > > + > > /* > > * same as bch_encode(), but process input data one byte at a time > > */ > > @@ -126,7 +169,9 @@ static void bch_encode_unaligned(struct bch_control *bch, > > const int l = BCH_ECC_WORDS(bch)-1; > > > > while (len--) { > > - p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(*data++)) & 0xff); > > + u8 tmp = swap_bits(bch, *data++); > > + > > + p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(tmp)) & 0xff); > > > > for (i = 0; i < l; i++) > > ecc[i] = ((ecc[i] << 8)|(ecc[i+1] >> 24))^(*p++); > > @@ -145,10 +190,16 @@ static void load_ecc8(struct bch_control *bch, uint32_t *dst, > > unsigned int i, nwords = BCH_ECC_WORDS(bch)-1; > > > > for (i = 0; i < nwords; i++, src += 4) > > - dst[i] = (src[0] << 24)|(src[1] << 16)|(src[2] << 8)|src[3]; > > + dst[i] = ((u32)swap_bits(bch, src[0]) << 24) | > > + ((u32)swap_bits(bch, src[1]) << 16) | > > + ((u32)swap_bits(bch, src[2]) << 8) | > > + swap_bits(bch, src[3]); > > > > memcpy(pad, src, BCH_ECC_BYTES(bch)-4*nwords); > > - dst[nwords] = (pad[0] << 24)|(pad[1] << 16)|(pad[2] << 8)|pad[3]; > > + dst[nwords] = ((u32)swap_bits(bch, pad[0]) << 24) | > > + ((u32)swap_bits(bch, pad[1]) << 16) | > > + ((u32)swap_bits(bch, pad[2]) << 8) | > > + swap_bits(bch, pad[3]); > > } > > > > /* > > @@ -161,15 +212,15 @@ static void store_ecc8(struct bch_control *bch, uint8_t *dst, > > unsigned int i, nwords = BCH_ECC_WORDS(bch)-1; > > > > for (i = 0; i < nwords; i++) { > > - *dst++ = (src[i] >> 24); > > - *dst++ = (src[i] >> 16) & 0xff; > > - *dst++ = (src[i] >> 8) & 0xff; > > - *dst++ = (src[i] >> 0) & 0xff; > > + *dst++ = swap_bits(bch, src[i] >> 24); > > + *dst++ = swap_bits(bch, src[i] >> 16); > > + *dst++ = swap_bits(bch, src[i] >> 8); > > + *dst++ = swap_bits(bch, src[i]); > > } > > - pad[0] = (src[nwords] >> 24); > > - pad[1] = (src[nwords] >> 16) & 0xff; > > - pad[2] = (src[nwords] >> 8) & 0xff; > > - pad[3] = (src[nwords] >> 0) & 0xff; > > + pad[0] = swap_bits(bch, src[nwords] >> 24); > > + pad[1] = swap_bits(bch, src[nwords] >> 16); > > + pad[2] = swap_bits(bch, src[nwords] >> 8); > > + pad[3] = swap_bits(bch, src[nwords]); > > memcpy(dst, pad, BCH_ECC_BYTES(bch)-4*nwords); > > } > > > > @@ -240,7 +291,12 @@ void bch_encode(struct bch_control *bch, const uint8_t *data, > > */ > > while (mlen--) { > > /* input data is read in big-endian format */ > > - w = r[0]^cpu_to_be32(*pdata++); > > + w = cpu_to_be32(*pdata++); > > + w = (u32)swap_bits(bch, w) | > > + ((u32)swap_bits(bch, w >> 8) << 8) | > > + ((u32)swap_bits(bch, w >> 16) << 16) | > > + ((u32)swap_bits(bch, w >> 24) << 24); > > We should make the bit swapping conditional (only do it if > bch->swap_bit is true) to not penalize the !swap_bits case. Sure > > > + w ^= r[0]; > > p0 = tab0 + (l+1)*((w >> 0) & 0xff); > > p1 = tab1 + (l+1)*((w >> 8) & 0xff); > > p2 = tab2 + (l+1)*((w >> 16) & 0xff); > > @@ -1048,7 +1104,9 @@ int bch_decode(struct bch_control *bch, const uint8_t *data, unsigned int len, > > break; > > } > > errloc[i] = nbits-1-errloc[i]; > > - errloc[i] = (errloc[i] & ~7)|(7-(errloc[i] & 7)); > > + if (!bch->swap_bits) > > + errloc[i] = (errloc[i] & ~7) | > > + (7-(errloc[i] & 7)); > > } > > } > > return (err >= 0) ? err : -EBADMSG; > > Oh, and we should patch bch_init() to take a bool swap_bits. I'm not > comfortable having users set bch_control fields on their own, > especially one that's marked 'private'. Oh yeah, I had this in mind but I completely forgot. I'll do it. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/