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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 EDC68C5DF60 for ; Tue, 5 Nov 2019 18:21:15 +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 B3BB9214D8 for ; Tue, 5 Nov 2019 18:21:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="f8ySWR4D" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3BB9214D8 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=9lgJnrgd3nHOEzxwVamRaos35QGHdeC2mjBh5rcMwE0=; b=f8ySWR4DkdRARo aWGf6DbGjlMyjMRcc55nfyk3f1M7CvcyLxsNK5QoQMtplFm2r/HgyDGnGSFIbzSQBPMypXEH2JIC/ Ce85GsHF/TaZG6X+wFDSmWh1b26UWJvZ7V0/+2eq9FaN8iBfEeu7H9crgj1iGyccCuEbXNDfaTBKz 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<20191103142741.7b2a2bf0@collabora.com> References: <20191016013845.23508-1-gch981213@gmail.com> <20191028174131.65c3d580@xps13> <20191103142741.7b2a2bf0@collabora.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.3 (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-20191105_102051_069023_0C9C72C8 X-CRM114-Status: GOOD ( 28.48 ) 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: Stefan Roese , Vignesh Raghavendra , Boris Brezillon , Chuanhong Guo , open list , Frieder Schrempf , linux-mtd@lists.infradead.org, Richard Weinberger , Brian Norris , Jeff Kletsky , David Woodhouse Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-mtd" Errors-To: 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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 1D445C5DF60 for ; Tue, 5 Nov 2019 18:20:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EED5B214D8 for ; Tue, 5 Nov 2019 18:20:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390796AbfKESUi convert rfc822-to-8bit (ORCPT ); Tue, 5 Nov 2019 13:20:38 -0500 Received: from relay12.mail.gandi.net ([217.70.178.232]:40383 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389356AbfKESUi (ORCPT ); Tue, 5 Nov 2019 13:20:38 -0500 Received: from xps13 (unknown [91.224.148.103]) (Authenticated sender: miquel.raynal@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id B6C1820000A; Tue, 5 Nov 2019 18:20:32 +0000 (UTC) Date: Tue, 5 Nov 2019 19:20:31 +0100 From: Miquel Raynal To: Boris Brezillon Cc: Chuanhong Guo , linux-mtd@lists.infradead.org, Jeff Kletsky , Richard Weinberger , David Woodhouse , Brian Norris , Vignesh Raghavendra , Frieder Schrempf , Boris Brezillon , Stefan Roese , open list Subject: Re: [PATCH][RFC] mtd: spinand: fix detection of GD5FxGQ4xA flash Message-ID: <20191105192031.2847438c@xps13> In-Reply-To: <20191103142741.7b2a2bf0@collabora.com> References: <20191016013845.23508-1-gch981213@gmail.com> <20191028174131.65c3d580@xps13> <20191103142741.7b2a2bf0@collabora.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Boris, Boris Brezillon wrote on Sun, 3 Nov 2019 14:27:41 +0100: > On Sun, 3 Nov 2019 20:03:21 +0800 > Chuanhong Guo wrote: > > > Hi! > > > > On Tue, Oct 29, 2019 at 12:41 AM Miquel Raynal > > wrote: > > > > > > Hello, > > > > > > Chuanhong Guo wrote on Wed, 16 Oct 2019 09:38:24 > > > +0800: > > > > > > > GD5FxGQ4xA didn't follow the SPI spec to keep MISO low while slave is > > > > reading, and instead MISO is kept high. As a result, the first byte > > > > of id becomes 0xFF. > > > > Since the first byte isn't supposed to be checked at all, this patch > > > > just removed that check. > > > > > > > > While at it, redo the comment above to better explain what's happening. > > > > > > > > Fixes: cfd93d7c908e ("mtd: spinand: Add support for GigaDevice GD5F1GQ4UFxxG") > > > > Signed-off-by: Chuanhong Guo > > > > CC: Jeff Kletsky > > > > --- > > > > RFC: > > > > I doubt whether this patch is a proper fix for the underlying problem: > > > > The actual problem is that we have two different implementation of read id > > > > command: One replies immediately after master sending 0x9f and the other > > > > need to send 0x9f and an offset byte (found in winbond and early GD flashes.) > > > > Correction: Only early GigaDevice nand chips uses this implementation. > > Winbond chips uses a dummy byte instead of an address byte so there's > > no problem for Winbond chips. > > > > > > Current code only works if SPI master is properly implemented (i.e. keep MOSI > > > > low while reading.) > > > > > > I am not entirely against the fix, but this is a SPI host controller > > > issue, right? Can you try to fix the controller driver instead? > > > > I think this is a spi nand framework issue. GigaDevice uses an unusual > > READ ID implementation, and as a result, both host controller and chip > > are reading during the first byte after 0x9f command: chip is reading > > the address/offset byte and host is expecting the first ID byte. > > Here lies two problems: > > 1. According to the sequence diagram in their datasheet, MISO pin is > > in High-Z state during the 0x9f command and the offset byte, and host > > could read anything during this time instead of a fixed 0x0 or 0xff > > byte, so the check of first byte should be removed. This is what this > > patch is doing. > > 2. If there's a buggy SPI host controller that didn't keep MOSI low > > during reading operation, the chip will get 0xff as ID offset, causing > > the read vendor/device ID to be swapped. I never met such a controller > > so far, but if there is one, it will be a silicon bug that can't be > > fixed by software. To fix this one, we'll have to make a second > > read-id implementation in spi nand framework. > > I realize how fragile this ID-based detection is when manufacturers > decide to not follow the standard READID semantic (one 0x9f command byte > followed by 1 or more input cycles encoding the ID). Let's imagine you > have a valid manuf ID byte in ID[0], and the device ID (ID[1]) matches > the Winbond or Gigadevice manufacturer ID, and ID[3] (extended Device ID > byte?) matches a valid Winbond/Gigadevice device ID. If you skip the > check on ID[0] you might erroneously detect a Winbond or Gigadevice > NAND, while it's actually something else. > > Note that I don't really have a solution to make this detection more > robust. > > > > > The second problem only exist in theory, so my preference is to apply > > this patch and fix only the first problem for now. > > I think we should fix that problem now. Maybe by doing a 3 steps > detection: > > 1/ READID + ID[] > 2/ READID + DUMMY + ID[] > 3/ READID + ADDR + ID[] > > At each step we would check if the returned ID matches a valid NAND, > and if it does, stop there. I like the idea. That will be way more robust. Thanks, Miquèl